Full info on parts used, as well as other builds can be found here. Modular parts organizer in a lazy susan-style, for wire shelves. The stackable central "trees" can be stacked to fit the shelf spacing and have mount points regularly spaced along their lengths for attaching trays, compartments, etc. The ends of the trees sit in tapered roller bearings.

I have loaded the 12 compartment bins with fasteners and they have not yet had me cursing while I clean up the floor, but just to be safe I also made some clips that can be put between to compartments on the same level to take most of the moment off of the tree. I'd like to load test one to failure in the future, but for now, that's the best I can offer for 'how much load can it handle'.