If you've ever purchased mold-making silicone in a gallon size or larger, you realize how expensive this stuff can be. While it's amazing and worth every penny, I've been looking for ways to reuse the silicone and save some cash. I've heard of people grinding it up or sticking extra pieces in the top of a mold, but I want to share with you the method that I've found to be quite effective.

*** Please note that if you use a mold release, this method will likely not work. ***

So let's save some money, and cut up some old silicone molds!

Step 1: Cutting Up Old Silicone Molds

We're going to cut up old silicone molds into pieces that can be stacked inside our mold box. You'll want to cut up the silicone in different shapes depending on the shape of the piece you're molding. For me, I was working on a new prop - Chirrut Îmwe's staff (from Star Wars Rogue One) - and my mold box was narrow and very tall.

So using some kitchen shears, or even better for the thick areas, sheet metal shears, I cut an old prop mold into long thin strips.

Once you get the mold cut into strips (and get a blister in the process), you're ready to start stacking the pieces inside the box, like a Tetris pro! I've put together some illustrations on the following step.

Step 2: Stack the Pieces

Since it's difficult to tell much of anything from the top of my mold box, I decided to 3D illustrate how this works with one side cut away from the mold box.

In the first illustration, you'll a render of one side of my Rey Staff Prop. As the images progress, you'll see how I stack the pieces of silicone. Since the silicone is made to pick up every detail in the prop you've created, the silicone should easily travel down into each of these cracks. Once you run out of old silicone to stack or you get to the top, you're ready to start pouring in the new silicone.

So let's pour some silicone!

Step 3: Pour the New Silicone

When it comes to pouring new silicone, I choose to work in steps, tilting the box from side to side, to free up any bubbles that might have been trapped under the prop edges or the old silicone pieces. Depending on the size and shape of your mold box, this may not be necessary.

Using this method, I was able to drastically reduce the amount of new silicone needed, and I was able to save a considerable amount of money in the process of building a new prop mold.

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Have you tried it, or is there a different method that works better for you? Let me know in the comments!