Sculpey is a great material that is rather strong when used
correctly. See if you can get a toaster oven to use right in your
artroom. You can sometimes find them at garage sales.
If I recall correctly,.....I had the kids put their work on a piece
of aluminum foil, and slightly roll/fold up the sides to form a
container. They could write their names in the foil with a ball-point
pen - or perhaps on a piece of masking tape. If the kids drew a
little thumbnail sketch of the pin beforehand, that would also help
Sculpey can be toxic if baked too high. Make sure you know your oven
and don't bake it over 275° as people have already mentioned. Smoke,
excessive fumes and browning indicates overheating.