Sam's reviews make you feel as if some mate of yours called you over to show you a new model train he bought. The videos are so oddly conversational. Thanks for the great content!

You have become worthy of the legendary “certified train enthusiast” award

I honestly think it looks pretty good. With the pre-shading, it looks like a wagon that's been in service for a few weeks, a bit of dirt is gathering but it's still in good condition

Looks many times better, and will look better still when the chassis is painted too. Next weathering !

Long have I waited to see your foray into this. So glad that it finally happened. And you splurged on an airbrush, too! When I decided to paint my own stuff, I did it all by hand! EDIT: "You can see what it looks like compared to some better wagons" - Sam don't be so modest. It looks fine next to all of them. Oh sure if you get up close it doesn't have the same detail but from most of your camera angles, the painted wagon fits in *perfectly*. And looks less plastic, too!

Great work Sam, I would love to see you 3d printing a dmu to run on your railway and then paint it in a custom Sam's trains livery!

Everyone has to start somewhere, and to be honest I really don't think it's too bad. Much better than something I could do!

i thoroughly recommend you get a decent mask, eye protectors and an air extractor as some of the chemicals (thinners etc) can be toxic.

If the primer's pooling as you describe, you're applying too much, possibly at too close a range. A few thin coats is far better and will avoid pools and runs.

COMPRESSOR WITH A TANK IS A VERY GOOD ADVICE a very talented artist friend explained that compressors produce air in pulses which makes air brushes splatter. the tank absorbs the pulses and the pressure regulator lets out a smooth supply of air. top marks for trying and if at first you don't succeed, just keep trying. all the best Roy.

It really came out nice! One suggestion when spray painting, either with an airbrush or can: Always have the paint spraying out before and after the piece you are applying color to that way you get a much more even application. It also helps avoid any drips. And that is true for a little model or a large piece of furniture.

I think that was great for a first attempt and seeing as how you designed and produced the wagon body and chassis yourself too, you should be very proud. Also your candid humble approach makes me feel more enthusiastic about giving airbrushing a go. And think how much money you'll save on wagons and coaches!!

Great video Sam! As a fellow airbrush painter in the plastic model world it was certainly interesting to see your take on the method! I do have one tip, and that is if you fill your brush with cleaner and hold your finger up to the nozzle to seal it and spray, you can "gargle" the brush which has a highly effective cleaning effect. I hope that helps speed cleaning up for you.

Great to see you having a go at the Airbrush. I must admit I am a little bit of a learner too. But I have some tips for you from what I have learned. 1. Do light colours first as darker ones will cover mistakes easily but not the other way round. 2. Pick the right primer I find that if the majority of the piece is light coloured using a white primer is best but nearly everything else does good with a grey. 3. Try diffrent brands and see what works best for you. I use Valehho too and find it works for me but others use MIG or Revell. I know some even use Enamel Paints 4. Don't push to hard at the start. Work yourself up to the harder stuff otherwise you will knock your confidence. 5. With my Paints I have found a 66% Thinner 33% Paint works well. But im still tring out with my Compressor. 6. Watch other peoples turorials they are a great help. 7. Some parts will be best done when you have not assembled the car yet 8. Some parts are best done with a good quality Brush and done by hand 9. Get some good marking out tape. I use Tamiya Masking Tape but use whats best for you. 10. Dont be afraid to mess up. Have fun mate.

great stuff, the Timbertech is a very good starter/low use kit, it does not have a tank though. Acrylic paint tends to block the needle/jet on all airbrushes. Acrylic thinners are just a third IPA 2 thirds water and a tiny drop of Fairy Liquid so make your own for a few pence. Enamels work better, enamel thinners are 80% white spirit and 20% acetone so make your own for a few pence. Cleaners for both types of paint are 50:50 mixes so make your own. You should be wearing a good quality filter on your face and an extractor fan system is required if you don't want paint dust everywhere, good luck

Sam you could be the ultimate trend setter, by showing people what's possible, others will jump on the band wagon (no pun intended), and could even make the big manufacturers (hornby, bacchman and the rest) sit up and take notice. Just imagine if there was an open source forum for people to share home made designs of waggons, coaches and loco bodies or even collaborate together to make and improve designs? Surely it would put serious pressure to reduce prices from the big manufacturers (personally I think they are well over priced) if everyone was making their own stuff.

Sam, I’ve be airbrushing for over 50 years. Have to start somewhere, and practise, practise, practise. Get a cheap plastic model and play! You can overpaint many times to try different effects etc. The main thing - have fun!

Well done Sam, good job, glad to hear that you enjoyed it - nice to see you progressing. Word of wisdom to the wise, even with low VOC (low odour) paints, such as acrylics you shouldn't breath in the spray. It's akin to breathing in microscopic plastic particals, small touch in jobs at low pressure are okay, larger areas and you need proper filtration. Some filtered spray booths can vent via a pipe to fresh air and others can filter the air back into the room. Both types can be had cheaply these days - just make that you choose one that has spare parts availability such as replacement filters. I hope that helps.

Excellent video, I have several brass kits to make and paint. The soldering of brass and white metal is not a problem. I have purchased an airbrush kit and now have to get the courage to use it! Your video is perfectly timed. I guess some practice on my part will give me the confidence to do the paint jobs that I have ahead of me.

Hi Sam- great review (as usual!!) - all I would say is airbrushing is a art within its self which you cant learn overnight - i,ve been using both a single action and double action airbrush,s for well over 20 years and i,m still learning lol ! all I would say is there are no hard and fast rules - its all about patience, practice, experimentation, patience, practice, experimentation patience practice experimentation and even more patience practice and experimentation -(nozzle sizes ,needle sizes, paint/thinner ratio different air pressures different paint manufactures enamel / acrylic paints etc,etc ), and then see works just what works best for you personally - I would maybe suggest you use a few old scrap wagon /coach/loco bodies to practice and experiment on ?- and dont give up as their WILL be some VERY frustrating times when you feel like throwing the whole lot in the bin !! just stick at it and you will be rewarded with fantastic results!- their is a paint range called "RailMatch" ,made by Howes of Oxford and they produce a VERY comprehensive range of railway colours that is worth checking out !! and finally- the very best of luck Sam - im sure you wont be disappointed with your results !

Talk about coincidence, I literally just ordered an airbrush myself this morning.

Kudos to trying something new! It is VAL-EH-HO. And you'll need the big bottle of thinner.

Great vídeo. You may want to build a spray booth. I used a box for a larger microwave and put a larger hole in the back then added a good fines micron funace filter and a box fan to pull the air and paint fumes fumes out. I duct tape all seams and added a led light inside. Works good when I airbrushed with out it in my train room you could see a haze in the air and I believe it left a thin coating on everything around it.

This is your best video yet Sam. I’ve done bits of kit building and kit bashing with 3D prints but never done my own 3D printing or tried air brushing. I love these videos where you try something new. You have a way of presenting that makes a daunting project seem accessible. I now want to get an air brush and give this a go!

Some possible advice for the future: - The protrusions you painted first should be done last, and might benefit from hand-painting with a fine brush rather than risking it with an airbrush. - It may be worth looking into some grey, white, or black primers - which will require fewer coats to fully coat. The yellowish one you used is fine for wagon bodies you intend to paint brown, but it would cause headaches for things you intend to paint in lighter colours. And finally - consider weathering dust in future, a very small amount applied sparingly can make even a mediocre paint job look much better :)

Awesome video. Of course you designed a perfect holder for the body while painting it. It is awesome how 3d printing can get you into so many more hobbies. Very glad you got a 3d printer.

Perfect timing! I got the very same airbrush a couple of weeks ago and have just started attempting to weather some old wagons.

I just knew you would take the next step and get an airbrush, Sam! After I restarted model railroading about a year ago I found out that my favorite paint was no longer made. So I got a Vallejo Model Air paint set just as you did and started relearning airbrushing. Usually you can use the Model Air paints without thinning (or just a little bit). However, I strongly sugggest you get some Vallejo Flow Improver. This is an additive that helps prevent tip dry in the airbrush and so reduces clogs. Use 1 drop for every 5 to 10 drops of paint. My airbrush has a 0.4mm needle and I use 20 psi air pressure. You did a great first job and I know you will gain immense satisfaction from airbrushing your 3D printer creations. Cheers from Wisconsin!

I have the same set up, and bought it off Amazon about a year ago. Like you I am by no means an expert, but have been messing around with it. I am impressed with it haven't had a problem, but keep in mind I am still learning. I have been using alcohol as a thinner with the larger tips and not have a problem as of yet. Don't be afraid of mistakes you can cover it up.Myself unlike you haven't made the jump to 3D printer yet, that is intimidating to me. I will be making a purchase by the end of the year, just kind of hesitant at the moment, would make my lay out that much better making my own little knick knacks around or doing what you did and make your own cars from scratch. Keep up the good work, and I'll keep watching.

Very good that sam From 3d printing your wagon to literally painting your wagon it looks good on KZfaq The more you practice the better you get , I enjoy weathered locos and I understand why some don't do it maybe we could see a fleet of your wagons in your videos

That was a great introduction to airbrushing. I'd love to learn that stuff myself. Some model railway KZfaqrs create amazing results with it.

Grab some of Vallejo's European Dirt and spray a mist around the bottom of the wagon, spraying in an upwards direction. It will give the wagon a weathered look. Also give the roof some shades of different darker gray to age it.

Switched on KZfaq this morning to research airbrushing. Lo and behold your new vid was top of the ‘recommended’ before I even had time to search. A great presentation, highly informative and useful, showing me exactly what I was looking for. Thank you.

Love the real time demo. Thanks.

Absolutely loving this 3D printing series and now painting vid! I'm considering to buy a 3D printer myself and this is making me even more excited to do so. More of the same please. :D

The wagon looks like it is brand new fresh from the factory before wear and tear settled In. A little tip take 2 colors and combine together in a bthey're in a blank bottle and slowly add small amounts at a time to get a more rustic rustic and weathered color of paint. Is like mix a little rust and mud Brown to give it more of a rusty wood look.

Great job Sam! I have an air brush on my wishlist so you have encouraged me to have a go. Your wagon looks great.

You know what they say Sam, rule 1, it's your railway and if your satisfied for a first attempt, then thats all that matters. Great job

Apart from the shade of brown, I think your wagon looked better from a distance. It gave a nice, weathered impression.

Got to say Sam, in all the many months (years?) I have been watching your videos, this was the one I jumped on fastest! I have been making model kits during lockdown and painting them using rattle cans. I also dabbled in painting 3D printed wagons, one of which is now on your wall of train. However I have always known I was going to have to try airbrushing and watching you has convinced me it’s going to happen sooner rather than later. What an excellent result you got and the last shots with the wagon running in a train with other models does you proud! Fantastic stuff.

glad you finally gave this a go Sam! looks great for the first time. I bought my first airbrush this year as well and I have fallen in love with it. Such a great tool for modeling =)

good start there Sam. I never tried an airbrush myself, but I am tempted after seeing that. All that wagon needs now is a black wash, very very watered down black paint slapped all over and left to collects in the detail, then a very fine either dry brush over the top with a colour a little lighter than the base colour, then some lettering. I used presfix water slide decals, they are fairly cheap, I have a GWR wagon sheet that has enough on it for 30 or so wagons and costs about eight pounds from Hattons .they are also easy to use. The P:resfix range is pretty diverse with most main pre grouping, post grouping, various BR periods, some private owners and some general lettering styles covered, and there are other manufactures with similar products. give it a go, and a couple of coats of matt or silk varnish over the top is good to seal mit all in and protect the results. I await developments with intrest

hint with those compressors, from one who has burnt out two of them.. Don't run it for more than about ten minutes at a time without letting it cool down - the ones with air tanks are better, but even then. otherwise the seals inside gradually destroy themselves and it stops holding pressure. they are however aside from that, very good - if you don't want a tank a long air hose can work well for smoothing the airflow out incidentally that is a very good paint range, its also huge - they do the thinner in 200ml bottles, they also do a lovely range of coloured primers that are well worth getting - they are very smooth primers and can go through the airbrush, they won't "fill" but when I got a compressor it was to save money on rattle cans for priming, undercoating and applying varnishes - its saved a fortune so far

Know where you’re coming from Sam, I’ve bought an airbrush a few days ago the difference between yours and mine is that mine is a cheap battery one not used it yet though, no compressor needed. Mine is for my wargame figures 1st world war eastern front by the way the paints are from a Spanish company it’s pronounced Valleyo and they are one of the best.

Sam...It is vital that you have very good ventilation. I suggest you invest in a spray booth. It has a motor that sucks the toxic fumes away from you. You MUST wear a proper face mask, not the cheap paper ones. I use a professional face mask with straps that create a seal around my nose and mouth. You must not (sorry for being bossy but I like you) compromise in this area as even the cleaning fluids will play havoc with your breathing. I always use my airbrush with all my windows and doors open and a face mask. Have fun.

So, you are now an expert - intro wasn't wrong after all!! Very informative. I've always considered taking the hop into getting an airbrush since running R/C cars and trucks nearly 20 years ago. This video nearly tips the balance for me. I do notice better quality 'rattle cans' are available nowadays as well. Love the better precision of the airbrush. Al.

This is just what I needed! I'm looking at buying an airbrush so that I can learn how to weather my track and some of my wagons. Can't wait to follow you on your airbrushing journey and I've already learnt heaps! Well done for giving it a go and thanks so much!

Really great video again. But, check your instructions spray painting kit looks very similar and it does state in the instructions not to push the needle through from the back. It said to remove and install the needle from the front (I think so you do not bend the tip on the push button). I also used house water-based acrylic paint. Test pots to be more precise. I mixed the paint at 1/3 water to 2/3 paint. This meant I can wash up in water also. The test pots cost $5.00 Aus (about 2.70 Sterling). It is certainly a step up from brush but I will be combining both air and brush. You would have to have a look at your video and your wagon looks very respectable. Keep up the great videos. I love the stand you made to fit your wagon to paint it. Brilliant idea. Thank you.

I am glad you are learning and growing, and you come across as a decent bloke. Since so you have so many followers, if you continue to up your game it will encourage others to build layouts.

A useful and interesting video. I have recently acquired an airbrush but I have yet to try it. One useful item I have created is to fit crocodile clips onto the end of some thin wooden dowel (you could use old paintbrush handles) and they make a very handy means of holding small items while spraying. They can be stood in a jar or tin while the paint dries.

How encouraging…..Thanks Sam, a brilliant first effort, but more importantly it’s this kind of video that inspires us to give it a go!!

Excellent video. I just got an airbrush and compressor haven't tried it yet but video has given me the confidence to give it a go.

Sam, as usual a very entertaining video. Like you I am terrified of painting, and rubbish at hand painting. You have certainly provided me with food for thought. I wish I had an attic like you. I don't have a train set but I enjoy sharing yours because your videos are like going round to a mate's house to see what he's up to. Looking forward to watching you paint the rest of 'your train set'.

I have one tip and that is the type of tape. I use something called painters tape and it is blue. It is not as sticky as masking tape so it reduces the chance of damaging the underlying paint. And I am no pro!

my Uncles lorry that he drove had an air compressor with a nozzle that was used for Blowing the Dust out the Air vents and to blow dust off the Dashboard But when I sat in the Cab When it was at a truck fest I used the Air compressor to keep cool and style my Hair I gave myself a Small Mohawk and I walked from The truck show with a small mohawk and it was fun while it lasted

Good to see you starting to get into this sort of job you haven’t done a bad job there. I personally prefer manufacturer weathering because they don’t go overboard with it and make it look really dirty like a lot of other people tend to do. Need to get an airbrush myself one day.

I just started painting my trains. The only thing I have done so far is paint the cabs and some little details, I'll email some pictures of them to you so you can see them

Great video sam i love how you make your videos funny in some sort of way! :D

Well done, you have taken on the next challenge, like the 3D printing takes time and practice. Great stand for putting your printed wagons on, that will help far more as you get better and more confident. Who knows with time you make start repainting the railway buildings!! Again good honest video, well done for taking on a major step. All best and looking forward to a full rake. Marc

I just love your enthusiasm Sam and can't wait to see you attempt some weathering next 😁👍

Sam, you did a great job, especially for the first time with an airbrush. I am impressed and look forward to more videos like this!

Very solid job Sam! I just got my first loco in the mail and though I'm gonna be repainting it using brushes, this is definitely something I'll have to try once I get further into the hobby. Best of luck on improving your airbrush skills!

Great video Sam, very informative. Thanks!

It actually looks fairly nice :D it reminds me of some of our old italian "F" wagons, the brown you used looks really really similar

Sam you could have said here’s one I prepared earlier, regarding the under coat . Excellent channel you have become my go to review channel .

Sams new channel: painting with Sam Channel description: Bob Ross, but for OO/HO scale/Guage trains Fun fact, I use .5mm pens to write incredibly small (less than a millimeter), I don't have an airbrush, and eventhough it takes me a long time, most of my weathered present day BNSF equipment is weathered using .5mm. Incredibly fine.

Another great video there sam.Very helpful like always.

Bought my first Airbrush kit ( very similar to yours.) And have never looked back. You can pay the Price of a Kidney for a Special Airbrush its self. But I have never found a use for it myself..! What you have will serve you well..! Have fun Sam..! Cheers kim in Downunder land..!! 😎

Good job! I got into airbrushing last year and it does give some nice paint finishes. That being said, I like to think my brush painting skills are still pretty good haha! If you ever fancied a collab, i could certainly have a go at custom painting some of your wagons for your layout 😉

Wow That looks great. And it's a first try. Well done. To get a very nice looking result on the first try is great. It encourages me to get out an airbrush which I purchased but have never used. Cheers.

Hi Sam, love all your videos. I'm a bit 'old school' and I'm into Hornby 3 rail from the 50's and 60's, All diecast locos which I suppose are a less realistic than modern stuff but I have used some modern ideas like Dapol lower quadrant electric signals which are really good. And I have tried making rolling stock and painting so this video is really interesting

I did some weathering on my old wagons... useing a brush only if i had a air brush

Vallejo air are already premixed for airbrushes they come with black lids .Some Vallejo come with white lids those u need to mix 50/50 with thinners for use with airbrushes.

What you didn't buy Sam, was a face mask to guard against breathing in the blowback which is invisible to the naked eye. If you're going to do a lot of airbrushing maybe get a spray booth too. If using acrylics then you should thin the paint with water. 'They' say you should use distilled water, but a friend of mine experimented and found that boiled water was just as good.

One day, you watch Sam restoring his Caledonian Single. The next, he's practically ready to start producing his own line of models. I hope that day isn't too far off because I would legit pay money for those! Whether or not you think they're good, their quality, charm and admittedly, novelty are well worth it to me! Edit: As a side-note, I think your paintjob looks a lot better than the ones on the vans you chose to run it with.

Perfect beginner's guide, presented by a true beginner ;) That doesn't look bad at all! You can totally save the color by adding some shading with inks with a brush (a technique called a wash). It will darken the tone and give depth to details. Handpick some details on the chassis with a metallic color, add weathering, and you have a 30 bucks wagon in your hand ;)

Great video as always Sam, much better than my first attempts with an airbrush. I obviously don’t know the layout of your house, but judging by the fact that there’s no windows in your loft I’d be careful with using airbrushes in a room with no ventilation, we the people still demand your train reviewing videos so I’d recommend opening a near by window or using a fan while you’re using the airbrush to avoid intoxication. Hope you have a great rest of the day however!

Can you please try weathering locos? It’d be fun to see and quite interesting to see how the weathering would differ from steam to diesels as obviously some techniques overlap but their exhausts and upkeep were quite different

For your "Mud brown", it's probably the right saturation, but a little on the light side. I mean, you could just try to use a different colour entirely, but... try adding in a couple drops of black to the mud brown, though looking at it next to your other wagon, maybe a add a little rust brown too?

¡¡¡Felicitaciones por animarte a pintar tus vagones!!! yo compre el aerografo, las pinturas, el primer y el compresor de aire hace mas de un año y aún nunca lo utilice, tengo miedo de arruinar mis modelos jaja. Saludos desde Argentina

I don't even paint trains (I paint Warhammer miniatures) but I'm stoned and your humour at the beginning of this drew me in. I may order a model train kit to paint because if you.

Excellent work Sam can’t wait to see your other 3D wagons sprayed just like your 3D printer another worthy investment

I've been experimenting with hand painting in N scale with much success, looking at getting an air brush so this video is great help to me

Sam, Good to see the baby steps; thanks for sharing. Vallejo is Spanish, so pronounced va-ye-ho Good to see you checking the pressure under flow; that's the right way, but not how most people set it up. I note that your compressor doesn't have a reservoir; it has a moisture/oil trap, but might still be pulsing with the compressor output. (The length of hose does help) You can build a small reservoir out of a Pringles tube, which will remove pulses from (even more basic) compressors.

Well done Sam, you’ve finally given it a go. That brown doesn’t look too bad. I should get myself a decent airbrush and compressor as I only have a cheap Humbrol one from many years ago and only ever used air cans with it.

I've got a few airbrushes. With the introduction of acrylics brings a whole new way of painting over oil paints. Stopping acrylics drying and clogging the nozzle is a must know knowledge. Many many videos on KZfaq on how to do this. Once you have the knack, weathering gets easier. Have fun. Spray booth is essential. Watch Martys Matchbox Makeovers. Bret Green's Testors scale model workshop videos are very informative.

Hello Sam, excellent choice to start airbrushing! Your first painted wagon is more than good for a beginner! Although, acrylic colors are sensitive and must be "sealed" after painting, to avoid paint chip, with a layer of varnish. Continue with weathering! (Practice makes perfect!)

Great video and great result ,I figured I could give my tuppence regarding paint tips.You saw you have a "satin varnish" bottle in your set.This is used on any of the colours to provide an intermidate gloss or shine to the colour.normally there is 3 types of finish to a paint , matt ( or flat) satin ( or semi gloss) or gloss.unless it states on the paint otherwise your colours are matt ( or flat) finish and the satin varnish gives the option to make them semi gloss.matt = dull flat, gloss = shiny new car ...satin/semi gloss inbetween.

I bought one of these airbrushes for my rc and its perfect. Keep up the great work If you want to do decals look at cricut. Its a small vinyl cutter

Excellent. Well done Sam

My parents got me an airbrush for christmas, including some mixing pots, but no cleaning kit. I haven't yet used it. I also use sea grey for wagon roofs, although I use humbrol 27, but so far I've just used regular brushes. BR grey I just humbrol 1 grey primer, but BR bauxite I couldn't find an accurate match for the colour used by bachmann (although 70 Brick Red is a good match for a faded version), so I mixed my own using various different paints, and I vary the shade by mixing a bit of something else in so wagons don't match each other exactly.

Sam that is way better than I could of done and I think the colour is good well done

Hi Sam, happy new year, enjoy your videos, a tip for you for air brushing buy some white plastic spoons you paint them with primer or leave them as are when dry { just pull back airbrush leaver} you then paint your colour on to it, several thin coats should work, then do same with the varnish as this will protect the paint like they do for cars. also you can then do weathering and dirt and then apply varnish to that as well . hope this helps keep up the good work.

Very nice Sam, just by looking at the thumbnail that wagon looks realistic

Hi Sam. I brought the cheap Amazon/eBay airbrush and it almost put me off of airbrushing. I spent a little more and brought an iwata. Different game now. Good luck chap.

Word of advice for everyone Sam....I originally was going to go for one of these complete kits but in the end I went for a better compressor with a reserve tank. The compressor does a lot less work....more stable air supply and it stays cooler. Buy the best airbrush you can! I finally settled for a Badger PATRIOT 105-1 for £87.00 It is a life changer :-) so much better than the ones in any kit! It will spray virtually any acrylic paint suitably thinned so you don't have to buy those very nice but expensive Vallejo air paints... Check out the reviews .. Worth every penny! Best regards David

Color palette charts can help with colors. A good first try. Really enjoyed this video. I hand paint my hand made wooden rolling stock. Keep up with all your content. Thumbs up !!! And I am still learning.

I'm a fairly seasoned modeller so I have quite a bit I could input here to help. First off, that was a fantastic job for a first attempt. Seriously good! Unfortunately your compressor does not have a tank on it but it shouldn't be an issue. I build model aircraft primarily and pre shading is used extensively on scale models. However, it is typically used in the opposite way than you used it here. The goal of pre shading is to create shadows and darker areas where dirt will naturally build up. So for this wagon, pre shading small precise lines around the edges of the raised structural bars where they meet the planks on the side (instead of on them as you did here) and perhaps on the joins between the planks themselves but you would need to be very precise. When painting over pre shading its advisable to use thinner paint as you can control how opaque it is much easier and controlling how much the pre shading shows through is much easier too. I personally achieve a pre shaded look via black basing all of my models then spraying a marble cote inside all of the panels, leaving the panel lines black. I then do light coats over that to achieve the effect I want. This also gives the added bonus of having some tonal variation in the paint finish inside the panel lines which just makes it look less monochromatic. Painting technique is pretty good but its generally advisable to not do what you did when painting the roof at 24:18 as you went over the same area multiple times leaving the rest blank which makes it much harder to get an even finish. Plus that can also cause the paint to pool on the surface. If you want an uneven finish its better to do a previously mentioned marble cote underneath as it looks more authentic I suspect the primer pooled on the bottom of the wagon because you applied too much at once. I would also strongly advise on getting some Tamiya masking tape. For something like the roof of this wagon cheap tape like that will do the job because the roof forms a natural barrier and the tape just catches any overspray but the moment where you need to rely on that edge it will bleed like crazy which is why everyone in my modelling group uses Tamiya tape

Good work! A little bit of extra prep sanding down the first coat of primer then adding a second would go a long way in smoothing it out even more.

That airbrush is the same as my first ever one. Great video. I'd say a mix of brushes and airbrush is how I like to paint. I build model kits as well as the trains. I use Tamiya paints.