To prepare the master part, first wipe down or wash the item. Once clean and dry, apply a release agent to the original item—this will ensure that the master part will pop free from the mold. Coat the item with a layer of bubble buster—this product prevents the formation of air bubbles around the master part. Place the master item into a heat safe container. The container must be slightly larger than the item.
Heat the material for short intervals, roughly 15 to 20 seconds, until you understand how the microwave affects the materials. If you do not have a microwave, you may use a double boiler.
If you are unsure how much you will need, use the entire bottle of 100% silicone. [2] X Research source
Applying a release agent to the master item will make it easier to remove from the mold.
While the mold is curing, it is essential that the master item remain within the mold. [5] X Research source
Cut 4 to 6 sheets of plasters. Each sheet should be 6 inches longer than the mold. Layer the sheets on top of eachother. [12] X Research source Dip the sheets in bowl filled with room temperature water for 1 second. Remove the excess water by squeezing the sheets over the bowl. The sheets should be wet, not dripping with water. Lay the sheets over the mold and up the retaining walls. Press the sheets into the mold so that they form to the shape. Crease the edges along the retaining walls into crisp 90° angles—the plaster sheets lining the retaining walls will serve as feet. [13] X Research source Allow the plaster to cure for 30 minutes. [14] X Research source
If the key alignments do not come off with the clay bed, remove these as well. [15] X Research source
Apply a release agent to the master part. Attach the top of the mold to a retaining wall. Coat the master part in a layer of molding putty. Attach the bottom of the mold to a retaining wall. Create a mother shell out of plaster sheets. [16] X Research source
Newspapers are not advised as the print could come off on your molds or your finished plastic parts. You may also cover the surface with a trash bag or an old vinyl tablecloth. [18] X Research source
If you are using a pre-made mold, wash it thoroughly under hot water to remove the film of cornstarch. Dry it with a clean cloth. Coat your mold with a layer of release agent. If you are using a 2 part mold, coat both sides and reassemble it. [19] X Research source
Retrieve 2 plastic disposable cups. Determine how much resin you will need to complete your project. Pour equal parts A and B into cups 1 and 2 respectively. Pour the contents of cup 2 into cup 1. Stir with a wooden popsicle stick. [20] X Research source
