I've watched videos of home made cement mixers with baffles welded in the tub, a long with spraying the inside with truck bedliner. There were a lot of real negatives to doing it this way, - I believe because it was at such an angle that the brass didn't actually mix / get clean. You certainly can't use stainless media, it just sits at the bottom.
Even Jerry only uses the cement mixer as a 'pre mix' to clean, and he uses corn cob tumbler after he dries it out in an oven. When you're doing five 5 gallon buckets at a time that's the method I would use too, but for me the multiple "smaller" batches in my Thumbler Model B works fine.