I have two metal shelf sets, actually the old high school gym class shelving that had wire baskets for your gym clothes. The shelves are rather close together, not much wasted space. I took four of them and bolted pairs back to back and installed them on angle iron frames with casters. One set has most of my odd ball tool items that I don't know what else to do with. Electric drill, screwgun, and elect impact, several different metric and fractional tap and die sets, three battery chargers, multi-meters in their boxes, cargo ratchet straps, a couple of bottle jacks, half mask respirator in the bag, safety glasses, face shield, pouched or boxed special tool items such as a huge ring compressor set of bands and pliers, large pullers, etc. long stuff like conduit benders hang on the sides and hoover portable 110v vac and shop vac accessories on top, along with circular saw, sabre saw, etc.
The other set of shelving has spray cans of paint, coffee cans with clamps in one, plastic caps and plugs in another (dirt daubers gotta be kept out you know) and several others with various things in them. Bottom shelf has two plastic cat litter trays with grease guns in them.
I use the deep drawers in the bottom of the tool boxes for the smaller low use items. specialty tools I don't mind digging for, clutch disc alignment tools, slide hammer puller and ends, old dwell meter, compression testers, door handle removal tools, oil pressure switch sockets, etc.
Charles