Like most people, I'm always in need of more tool storage space, but it's gotten really bad since I bought the mill. Unfortunately the shop is 99.95% full, but somehow I managed to clear-out enough room for a Harbor Freight 18" end cabinet. I've had the Harbor Freight 44" Red Roller for a few years now and it's been a good toolbox.
Of course, I don't have enough room to just hang the end cabinet off the 44" cabinet as intended, so I had to make a frame for some casters so it can be used as a stand-alone.
I welded some 2" square tubing for the frame as it fits the bottom cavity perfectly. Also cut some 1" tubing at 45's for the corners to catch the 4th hole of the caster brackets. All the holes were drilled and power-tapped on the mill for 1/4-20 bolts for the caster frames. The tubing is just 1/8" thick, but there seems to be enough threads for this application. The 5" swivel casters are from Home Depot and have a nice feature in that the lock brakes the wheel AND the swivel.
Before rolling the end cabinet into it's cubby-hole, here's a shot of it standing beside the 44" cabinet. Looks like it came out at about the same height.