What do you do with all those little crayon nubs no one wants to use?? Make new crayons! Preheat the oven to 150 degrees while children fill shaped tins with crayon pieces, arranging them in interesting designs. Bake just until the waxes have melted, 15 to 20 minutes. Remove the shapes after they have cooled. If they stick, place tray in the freezer for an hour, and the crayons will pop out.