Last week I managed to scrounge a used tumbler from the local Acklands store here, it's maybe 12"x18"x18" internally. It's a rotating square box with maybe 75 lbs of what looks like 3/16 stainless rod cut at around a 45 degree angle, each piece is maybe 1/2" long overall. It's in an enclosed half barrel that used to have varsol to keep the media clean and wash away grit and cleanings, etc. They used to use it to clean up connecting rods and similar small parts back when they used to rebuild motors 'in store', probably twenty years ago..
It hadn't been used since then, and when I was in getting a serpentine belt to upgrade on old South Bend lathe, I saw it under a pile of lumber in a corner..
Price was right, 'get that junk out of here now if you want it'
couldn't ask for better...
enjoy