I only briefly looked into TNT foam, but I figured for a first project I didn't want to confuse myself with different thicknesses, so mine's just flor mats from the hardware store. To be honest though, the shipping wouldn't be a problem cause I live so close to the states I often have stuff shipped to a friend there cause its cheaper. Even though the windsor-detroit bridge is closed except for essential travel, I can still get things across because my family knows enough nurses that cross regularly. That's actually how I got my 3D printer shipped. haha