I'm wanting to try this and don't know where to find it. Thanks!
Michael's craftstore has it so does most supply stores for art supplies.
Wal-mart has it too.
Walmart carries the 1/4" thick foam board, you can get 1/2" thick board at Hobby Lobby or Michaels.
AC Moore and Michaels (Michaels often has them on sale for 99cents, then I stock up)
Melvira told me that you can buy it from Logicpic in the shapes that you want. The only thing is that you have to order a minimum of $35. I hate it when companies make you do that. I'd rather just pay the extra money for shipping!
I've found it at the dollar store before.
watch acmoore and michaels ads... they mark it down to $1.00 a sheet for the 3/16" thick one... i get 15-20 sheets when they do this.. or more..