Making chocolate insect pupae

Manduca sexta pupae made of chocolate (Fall 2009)

Using food-grade silicone, I created a few 3D molds of moth pupae, which I then used to make tasty chocolate treats for Halloween. The photos below show the steps involved in the process.

First stage: create a bedding for the lower half of a pupa (which was first frozen, and then covered in a food-grade release agent. The bedding is made of sulphur-free sculpting clay. (No sulphur is important: the silicone won't cure if it comes in contact with sulphur.

Smoothing out the surface of the bedding and adding small pegs that will make it easier to align the finished mold. Notice the little piece of clay facing forward towards the edge of the mold. This will form a channel through which excess pressure can be released.

Building a wooden moat that will hold the silicone.

Before filling the moat about 1/2 way up (to the black mark I made about 3/4in above the top of the pupa), a thin layer of silicone is poured onto the pupa. This prevents air bubbles from being trapped near the pupa's surface.

Finished half-mold, after a cure time of about 24 hours, and after the clay has been removed. A second layer of silicone will be poured onto this half. Basically the previous step needs to be repeated for this. Don't forget to create an air-release channel (in my case: left of this picture, from the head of the pupa out towards the edge. Clay still need to be added here to form a round channel). Also, put some release agent on the silicone, so the two halves can later be separated more easily.

The second half of the silicone mold has been poured on top of the first one. After a cure time of aobut 24 hours, the mold can safely be taken apart. Be sure to give the mold a good cleaning (in the dishwasher) before using it with chocolate.

Finished chocolates (dark and milk chocolate varieties.)