I've finally got some foamcore, and found out it's called "papel pluma" here in Brazil. I got it as a very large (about 1m x 1m) sheet 4mm thick. So now I can finally try to make the foamcore miniature bases that some people on Cardboard Warriors use. I cut some 1" square bases with a slit across the middle, based on Okumart's instructions in the Whiplash Trigger sets. The minis fit very well and the base remains relatively flat. Then I tried applying some green paint to them, and here's the result.