Get a cheap rock tumbler from a place like Harbor Freight and some course aquarium gravel. Put a cup of water in with 1/4 drum full of coins and 1/4 of gravel and let 'er rip overnight. (Do not overfill the drum).
Soak in vinegar ( a mild acid ) and check every 15 minutes or so.
You can rub gently with an eraser or non-scratch pad the clean pots with.
Then rinse thoroughly, clean with alcohol.