Our Basic Coaster Mold 893 is made of durable, smooth, reusable polypropylene and measures about 3-1/4" in diameter and holds about 3 ounces of resin. Paperweight Base Epoxy Resin Mold Mould Casting 584 is made of durable, smooth, reusable polyethylene mold that measures about 4 inches x 4 inches x ½ inch and holds 6 ounces of resin. SOME BUFFING AND/OR SANDING MAY BE NEEDED ON THE FINISHED PIECE TO ACHIEVE A SMOOTH SURFACE. The deep side of the mold can be used to make coasters and similar castings but turn the mold over to its shallow side and you can use the same mold for a round holiday ornament or a dazzling suncatcher! How to Use Resin Molds: Remove any dust, etc. from your mold. This resin mold is reusable and made of durable, smooth polyethylene or polypropylene. Molds do not require mold release when casting with resin, however, it is strongly suggested. We recommend the use of Castin'Craft Mold Release/Conditioner. Instructions: Protect your work area with freezer or wax paper. Treat molds with mold release/conditioner. Place mold tray on a level surface. Fill the mold cavities to just below the top. Once the pieces are cured, turn the tray over and press the center area of each piece to release; flex if necessary.