These can be expensive . This came up on Golftechs forum site . There was a you tube post of some low budget home
Picked up a small palm sander Square ( 4 quarter paper )
Made a sheet metal plate to attach to sander using the tabs .
A little bending using a piece of 1/4 flat stock .
Trimmed down to fit and used hook and loop pads to attach to container and sander .
A little video of the action with sander . Tried a little concentrate soap and water and threw in a few pieces of tarnished copper pipe .
After agitating for 35 minutes it came out pretty clean . CLR was recommended for a solution which I'll be trying soon .