This is a Durable plastic that is made for Resin Casting. Pieces pop out easily-May have a few water marks, but a thin coat of resin or resin spray will take care of that. This awesome mold has 5 cavities! 1-3" long Skeleton hand 1-2 1/2" long anatomical heart Handmade by me 1-2 1/2" long bone 1-2" long brain handmade by me 1-1 1/2" skull Do not put in oven. Please do not copy or reproduce my molds. molded from love 2013