I've bought the gray sand that HD sells, and had to spread it out and put a fan on it for a week to get it dried out, they leave the bags out in the weather here in Seattle, so you get about 50% sand, 50% water, thankfully you're only paying for the dry weight of sand???Right??? The white sand that they sell as "Play Sand" seems to have been graded, at least to the high side, so you don't get stuff that's much bigger than 150 grit or so. (Oh for the days when Boeing surplus would plop a pallet load of silica sand bags out for 50 cents a 100# bag. It was worth drying, cuz that's all that was wrong.) I have used gray sand to clean cartridge brass with results that were ok, but not really that good, I don't know if it was because of the brass:sand ratio or running it dry, but I remember that I had to run it for almost a week to get the job done. That, in my opinion, was too long to wait for a 3 lb coffee can of brass.
I would suggest that you look around for some vibratory deburring media, some of it is like pyramid shaped soapstone, but I'm not sure what it is really, and there are other shapes available. They seem to have the weight to hit harder and cause a more agressive cleaning/deburring action.
As for the tumbler drum, make it out of something cheap, rubber coated seems to last the best, but PVC pipe is available and cheap. Five gallon buckets are cheap too, but how would you secure the lids??? Remember it is running on rollers and has to be contained somehow from walking off the ends. ?????
Almost makes you wish that you could remodel a front loading washing machine so that it would work. They seem to rotate at the right speed to make the load drop and slosh, which is why they work so well, I guess.