I almost got a degree in Chemistry until I decided Design was a better fit. I wanted to get in touch with my inner chemist, so I decided to make some theobromine shaped chocolates and show you how to make them too! Theobromine is a bitter alkaloid found in chocolate and other foods. It has the chemical formula C7H8N4O2.
Materials you will need:
Step 1: Preparing the original
The first step to creating our mold is making the original. (an original is the form that a mold is made from) I used a laser cutter to make mine so the first step will be creating a tool path for the laser cutter to follow. I made mine using Illustrator. The file is attached, feel free to use it or make up your own!
Through experimentation I found the best way to make the part was to laser cut the molecule and base as two separate pieces.
I used .125" thick acrylic for my original. Try to keep your material thin so it won't get stuck in the vacuum formed mold but thick enough that your chocolate won't break when you take it out of the mold.
Once your parts are cut out and collected from the laser cutter glue the molecules onto the bases. Try to keep them as centered as possible. I used a plastic glue, some options include plastic weld and epoxy.
After the parts have cured completely add draft angles onto the bases by sanding down the edges to about a 45 degree angle. This will help in releasing your part from the vacuum form mold.
The final step to preparing your originals for molding is adding air vents to the interior details. The vacuum form machine works by pulling heated plastic onto the part through vacuum suction in the bed. In order to allow the air to pull plastic in the center of the original you need to build holes into your part that let air pass through the part. You can further aid the vacuum by raising the piece off the bed very slightly by placing the original on pennies.
Step 2: Vacuum forming the mold
If you don't have access to a vacuum form machine here's an Instructable that shows you how to make your own.
The first step to running the machine is turning it on and allowing the heaters to warm up. This may take a few minutes depending on your machine, plastic and environment. As the machine is warming the plastic, place your originals on the bed (you may want to put pennies underneath the parts to help get more suction on the part).
Once the plastic has begun to sag a few inches it's ready to be pulled. Place the frame over the bed creating a seal and turn on the vacuum. This should pull the heated plastic onto the parts into all the details.
Keep the vacuum running until the plastic has cooled a bit so it won't deform. Once the plastic is cooled a bit turn off the vacuum and pull the frame off the bed. If any of the originals are stuck in the mold push them out.
Your mold is now ready to make chocolates!
Step 3: Making
First thing you will want to do is clean your mold. Although PET is food safe your originals might not be and the plastic may have picked up dirt on the vacuum form bed.
Now gather your chocolate making supplies
Set up your double boiler. Or if you don't have one use a DIY double boiler like I did. Place a metal bowl inside a pot (make sure the bowl is big enough to create a seal it's important that water doesn't make it into the chocolate)
Fill the pot with a few inches of water and place it on the stove at a LOW setting. It's important that you don't burn the chocolate so don't turn the heat too high and be sure to stir constantly.
Once the chocolate is completely melted use the brush to paint a thin layer of chocolate into the molds. Try to get into all the details. (brushing isn't necessary but it will ensure that there are no air bubbles in the chocolate)
Now fill the rest of the mold with chocolate using the spatula. Smooth out the tops and set them in the fridge to cool for about 15-20 minutes. Once they're solid pop them out of the molds and enjoy the theobromine goodness!