I do not know the answer to that because I have no idea what polystyrene is. Could you explain what this is? Maybe I could help then. Anyways, if he cannot eat it I would say that it should be ok.
ummm basically its used for packaging in tvs etc and its really easy to craft shapes into with a knife. Its really cool but atm i cant find anything to glue the pieces together without causing fumes so i guess ill have to throw it all in the bin!
Hi Danny ! Yes you can use that , most of us will use grout ( the kind for sealing in tiles on the floor and what not), start with a thin mix, and progressively make it thicker. When you have it completely covered ( usually around 7 coats,the last you basically have to plop on with a spatula or your hands ... fun fun !) allow to dry completely, then use polyurethane ( i used mix wax brand, the not fast drying) sprayed or painted on 5 layers thick. Once this is sealed in with the last coat of urethane, you are good to go to use this in the warm or cool side.
Hope this helps out !
Janie.