It works. I actually grated my own styrofoam particles out of foam cups, which is the part I would not willingly repeat. I first tried using our food processor to shred them, but it didn’t make fine enough particles. Then I put them through a cheese grater by hand, which did the job but left a lot of big chunks of cup in the mix. It’s possible it would have been easier with a grittier source of styrofoam, like the big chunks which protect electronic devices in a retail box, but I don’t want to find out. Incredible mess. I think I’ll see if someplace local carries the particles pre-ground.
Other than the styrofoam grating, it was a total piece of cake; easy and quick and straightforward to make, and I ended up with a very serviceable (if chunky) wad of floamy substance.
I’ll update tomorrow on how it dries. I made a smiley face out of a small chunk of it and left it out to dry.