I have an old cement mixer that I removed the mixing baffles from, I chuck in a couple of handfuls of sandblasting grit (or sand or pebbles depending on finish required) then put in the forged bits, Fit a lid to the mouth of the mixer (two discs of ply one larger than the open end, to fit over the barrel, one smaller to fit into the mouth of the barrel) secure these together with screws, than I made three clips to hold the discs in place, fit these to pevent dust going all over the shop, then let it roll, a little experience will let you know how long to leave the items in.