From the Green guide website:

#6 PS

Extruded polystyrene (#6 PS; commonly known as Styrofoam) is used in take-out containers and cups, and non-extruded PS is used in clear disposable takeout containers, disposable plastic cutlery and cups. Both forms of PS can leach styrene into food; styrene is considered a possible human carcinogen by the International Agency for Research on Cancer. It may also disrupt hormones or affect reproduction.

As we all know, the leaching happens, when the plastic is heated... I don't really know how harmful it is to breathe the stuff in that gets released, but it seems a little risky. Does anybody know?

Not to rain on the party, but could this potentially release toxins from the plastic?

My daughter and I tried this over the weekend. Wow - I forgot how much fun - and how easy - it is! And re-using the #6 polystyrene (that we can't even recycle in this area - only #1 and #2 are accepted) was a great bonus. We are sold on this and can't wait to do more and more! I will say, though, that I think ours shrunk down smaller than 1/3! Tiny, tiny! I will try to remember that next time!

Thanks for the tutorial! :)

This is great! I can't wait to try it. The first thing I thought of, application-wise was zipper pulls and cell phone charms. Ooh - are they thick enough to use for buttons? That could be fun, too.

Do you have a pic of the finished product?