Jonnfx I dont now what the material is called...I simply cut with a "break of blades"knife in the first layer(black) and glue the thin blue foam in the bottom because i want the 2 colour system! And under the blue foam i glue a regular carton piece because i want the tray to be stiff! And why i want it stiff is because i take the tray with me wherever i go...very handy! It is to soft without the carton and bends very easly!