I didn't cut it out according to a set pattern. Basically, I printed out that image on a full sheet label (sticker-y paper) and then put it on a foam sheet (a flexible one, around 2mm thick). Then I drew a grid on the back and just cut out random jigsaw-ish nubs with a utility knife. There are some disadvantages to this though, namely that the sticker paper probably peels off at some point, and the pieces are flexible so they don't "snap" like a cardboard one does. Probably, gluing a sheet of paper to cardboard and then laser-cutting it (or maybe making nub-shaped dies and hammering them down on the edges) would produce a better final result.
If you guys want to make your own glasses and have a surgeon's hands or access to a vinyl cutter, I can provide some instructions and the KS heart file for vinyl cutting - it's not too difficult.