Right sizing the bins are definitely the way to go. Having bigger than necessary bins may lead to excess inventory. Could the bins on the shelf be configured differently? Could the small bins be stored together and the big bins be stored together?

We have about 6000 bins in our 2-box system for WIP and FGI, so space is an issue. We learned to standardize the depth and the footprint of the core box size to efficiently fabricate shelving. There are several fractional box footprints (1/2, 1/4, 1/8, etc) for items needing less volume and still maintain an efficient allotment of space.

Keep the bins you have, just place the same sized bins next to each other = increases the appeal and keeps the function while maintaining the minimum amount of space being used. Regarding the KanBan Station... Is it so easy that someone off the street could do it w/o a single question?