I got the Harbor Freight tumbler for Christmas. I put in aquarium gravel, 3 or so drops of dish detergent, a little water. I let the pennies run for 2 hours, clad for 3 hours.
i am pleased with the results.
I read somewhere on here to add vinegar.
I do what stapler101 does and works okay for cleaning clad. Dont do any keeper coins as it can destroy their condition. I tried corn husk once and it takes a LONG time. It too can be found at pet stores.