I used the pee gravel, Dawn, and shaking method and it worked pretty well. For the next one I'm thinking about building a tumbler. I thought I would use a pair of plywood circles from Home Depot cut in two and zip tied to the flanges at the ends of the tank and build a cradle with four wheels to support it and power one of the wheels with a low speed motor. Then just throw some gravel and soapy water in it and go have lunch. The cradle could be built to also support a five gallon bucket for cleaning small parts.
