Courtesy of "The Professor"
Using the wooden strips, make a box around the glass plate. Seal off the edges using the window cement. Make sure everything is air tight
Place your record inside the box making sure that the portion to be copied is facing upward. Squeeze in some window cement to mark where the hole in the record is.
Mix the silicone (Smooth On OOMOO 30 or OOMOO 25) for about 3 minutes before pouring in to the mold.
Pour in the mixture. Start from one corner and let it fill-up the mold to about half a centimeter. Make sure it’s even. Let it dry for 6 hours.
Peel off the silicone from the cast. Cut off the excess using a cutter.
Pour the liquid plastic (Smooth On Task #4) on top of the silicone cast.
Make sure that nothing spills over the round form. You can also brush off any air bubbles that might occur.
Carefully loosen the plate from the silicone form. Using a drill press, bore a hole through the center of the plate. You can use the silicone form as a template to make more copies
There you have it. Your very own copy.