Its Monokote.
Stripes are cut from Monokote.
Checkerboards are Monokote.

I use a piece of glass to cut on. I take my iron and basically iron a piece to the glass, measure, and then make the cut for whatever I am doing at that point. The piece wont really adhere to the glass but it stays in place well enough to cut.
The checkerboards were cut out of black and laid over the white base. It didnt come out perfect but its good enough for the bottom.