Bernie says to place a card template over a Teflon craft sheet and lay down cut pieces of friendly plastic. I had some left over mixed and friendly plastic sheets (from a project I no longer remember) and used some of this in my project.
Use a heat gun to heat the plastic and fuse it together, I let it cool somewhat and pushed in the cute strips so the edges would not be completely straight.
Bernie mentions that you can fill in gaps with small pieces of friendly plastic and reheat. I wanted to add some thickness and more color, so layered on more bits of my flatten friendly plastic and reheated. When the plastic is cool enough to handle, use scissors to trip off any extra plastic.
If you want to add stamped images, reheat the plastic and impress with stamp inked with Pigment ink. Leave stamp in the plastic until it cools and stamp easily releases from the plastic. Reheat before each time stamping.
If the plastic curls up while it is cooling, use the heat tool to reheat and bend it flat.