If you cut up bits of sprue and stick them in a jar of acetone (usually in nail polish remover) then it melts into goo. It can then be used as putty and when the acetone evaporates the putty will return to a hard plastic. I've not tried it yet but the YouTube video was convincing.Nope. . . .this is just me. . . Bored and broke. . . Melting bread bag tags with the iron