Tumbling copper is needed to force the cleaning oxide against the glass for polishing.  The normal is cut from new 12-gauge wire into ³/32-inch and ⁵/32 -inch lengths. Fine is also available, which is cut from new 14-gauge wire into ¹/16-inch length.  Several mediums have been tested for cleaning, including buckshot, aluminum wire, BBs, glass beads, sinker pellets, etc., and so far, copper has proven to be the best.  Unfortunately, it is somewhat expensive.  However, once purchased, you will have the necessary amount and will only need to purchase small amounts as the copper wears down; this will be seldom in that the copper is completely reusable.

The following formulas can be used to determine the amount of copper you will need:
     1) Determine the number of canisters you intend to turn at any one time
     2) Total the largest combination of canister sizes that could turn at any one time
     3) Multiply this total by 4 and add 5
This will give you the minimal amount of copper necessary for your needs.

For example, if you purchase a two canister system, with a 4-inch and a 6-inch canister, you will need: (((4 + 6) * 4) + 5) = 45 pounds.