duckster, alra,

You can get 0.5mm, 12"x18" foam sheets on ebay. 4 foam sheets in olive, white, black and tan for $3.30 total.
Search for : 4 pieces 0.5mm foam sheets for fish fly tying or craft. The sellers name is owlonbeulah. I have bought a good amount of foam from her in various sizes and have had no problems with the service. She also has olive 2mm, 12"x18" foam sheets but you will have to ask her for this color because she does not have it listed.

Later, Jim