Mold Making: Two Part Silicone Mold

Step 2 Clay up

Once you've prepped your part for the show, it's time to lay up the first half of the mold. Draw a line that defines the very outermost edge of its curved surfaces. You want one continuous seam tangent to a majority of the curves on your part. The goal is to evenly split the part in the mold so it comes out easily without damaging anything. Also, molding this way will make the seam line easier to clean in your final part.

Find or construct a border for the part. You want it to be some sealed volume that at least extends an inch above the part, and an inch to the sides in all directions. I glued the top of a paper mixing bucket to a masonite panel with hot glue. Lay your part in this container securely with some clay. The clay is going to have a tendency to stick to your part, and will need to be cleaned when you begin the second half of the mold, so do yourself a favor and coat the part in a spray release, or wrap it in clingfilm and cut the film away at your mold line. Cleaning clay off your part will most likely result in it pulling up out of the mold before you begin the second half, which will mean that you'll get some silicone dribbling in between the part and the mold and screwing up your texture. Begin making a rough border around the part with clay, coming up to the line you drew earlier. Work the clay layer until it is smooth and even around the part. Leaving a texture to the clay will only make the mold harder to pull apart.