Making Your Own Silicone Mold

I love working with silicone molds because of the removal ease. When E. told me he wanted a Lego birthday party, I was on the hunt for some Lego brick molds. The only place that I could find them was on ebay for a highly inflated price. I would need to buy a couple of molds, and in the end, have to worry about the temperature (since the molds only work in temperatures less than 140 degrees). Even so, I was ready to click the "buy it now" button on ebay until I read a post on making your own Lego mold on instructables.

It wasn't until I did a little more research and found a local supply store that sold food grade silicone that really prompted me to make the leap and try making my own mold.  Amazon also sells the exact same Smooth-Sil 940 kit as well now.  I wanted food grade silicone because I knew I wanted to pour chocolate and make gummies from that mold. I ended up buying Smooth-Sil 940. There are other options you can find online like Copyflex, which I would have preferred to use because of the 1:1 ratio, but I was impatient and wanted to start right away, opting for what was available in the store. The Smooth-Sil 940 has a 10:1 ratio so a little math is in order when calculating how much you will need of each item.

Each package comes with two parts, Part A and B. You need 10 parts A to 1 part B.

I started making my Positive for my mold. I placed all the lego pieces that I wanted on a regular base plate. I surrounded the edge with two rows of legos to contain the silicone while it hardened.

In hindsight, I had enough silicone to make an entire lego baseplate, but I wanted to play it safe and didn't want to come out short so I made it a little smaller.

Since I had no idea how much silicone I needed, I decided to get a rough estimate by measuring with some alphabet pasta I already had in my pantry.

I filled my mold and then measured in a measuring cup.

Next came the math. I had to convert the 1.5 cups into lbs since you needed to measure part A in pounds and ounces. I had to convert that to grams to get the correct amount of part B since my gram scale measures with grams for smaller amounts.

I stirred part A before measuring it out.

Next, I added part B.

I stirred the two compounds for 3-4 minutes until they were completely mixed. It was so thick that it kept breaking my chopsticks. I suggest using paint stirrers instead. I didn't have any on hand so I used some disposable chopsticks.

After my great workout, I poured my mixture into my mold. The website suggests, holding the mixture up high and pouring over only one spot, allowing the silicone to spread itself over the mold.

In the end, I had a little too much silicone, so I quickly built a mini mold so that I could make a base plate using fondant or chocolate.

I let it set for 24 hours.

Then, the fun began. I removed all the lego pieces.

The pieces just popped right out

to reveal my negative mold.

I used a razor blade to clean out the edges since the silicone had seeped through the edges of the mold. Here is my base plate mold.

I envisioned having a huge base plate at the top of the cake so that prompted me to make this mold with my excess silicone.

I can't wait to start using my mold! In the end, the silicone cost of $35 was equivalent to buying two molds on ebay, but I was able to create the exact lego pieces that I wanted and more of it so I am super happy with my decision. Imagine all the things you can make with silicone? The possibilities are endless.