I'll make a harmonogram for you when I get home

Thanks! I am very picky about accuracy when constructing projects.

jrae2424 Yep - almost certainly your arms are the main problem. Ideal weight = approx. zero!! Try the balsa wood. I used a spherical magnet for the links - they sit nicely in the head of a Phillips screw and are low friction.

Ray McCon sorry for the delay in replying. I just saw your comment. I got mine at first4magnets.com I think

jrae2424 Look for any sources of friction. We used sharp pointed screws on metal for the fulcrums (if that’s the correct word). Reduce the weight at the pen so it’s not too heavy - make your arms as light as possible. We used balsa wood. They don’t need to be strong.

Using electric drill with an attachment I don't know the name of. It has a central pilot drill then an arm at 90 degrees with sharp angle point. Adjust length of arm for size of hole.

Two possibilities: just do 3 plots and change the pen each time (as shown) or put 3 pens together for a different, more random effect