Making customised chocolates using 3D printing

I was recently in search for an unusual Valentine's Day idea, came across silicon molds again and decided to give a go in the context of creating custom Valentine's Day chocolates.

First, I will say that that silicon moulds are a very impressive thing. They reproduce in details shapes, and are easy to use to recreate any object you may already have.
Second, the silicon here does not apply to resin. For I have only focused on FDM printers

Pre-requisites

• Food safe silicon. I used this one
• Mould frame. I recommend using this one as it offers great flexibility
• Silicon mat. I used this one
• Optionally you could use a heated mat like this one to accelerate your moulds solidifying. For now, I have placed mine near the radiators overnight (but might reconsider after the winter :) )

1. Create the model

3D print the desired shape: I 3D printed some custom shapes.
I also used a coin my son gave me to see how it dealt with intricate details (and it did like a chef! but more on that below)

If you are new to 3D modelling, you could start by using tinkercad.com. You could start with a basic shape like below (i.e. a shape and a message)

In this article, how about we use some code? Using OpenSCAD, you can use this gist code to generate the STL to 3D print.

2. Cast the mould

Prepare the mould frame

Start here so you can get a better idea of quantities needed to avoid wasting the silicon

Place the pieces you would like to print and assemble the mould frame around them. Make sure to arrange pieces in the space to optimise the size of the frame and overall layout (such as leaving sufficient space between pieces).
As a base at first, I used a plastic bag which leaves slight bumpy marks.

Now make sure to use the provided double sided sellotape to stick the frame, as well as each piece to the base. This will ensure the silicon does not escape outside the frame before it dries, and that the pieces will not move during the solidification process of the silicon. (The first time, some of the 3D printed pieces did move/ float, but generally did not stay stuck to the bottom and ended up with a layer of silicon in between).

Prepare the silicon

The silicon linked above is a 1:1 by volume, so you need the same amount of each liquid (part A and part B).

Make sure to mix it properly using the provided wooden piece. Stirring for some extra time, and every so often scraping the sides to ensure no liquid has been left unmixed may help get the most homogeneous substance possible.

Create the mould

Pour the silicon mixture slowly to ensure no bubbles get trapped, or the risk to move some of the pieces (although taped should be good enough)

Let it set for a few hours. When finished, gently remove the models from the silicon and let it rest for 24h (I saw the latter in the silicon's instructions and I assume this is part of keeping it food-safe, so I would encourage to do so to be extra safe).

3. Recreate your model in chocolate

Prepare the chocolate

For optimal texture results, it is advised to "temper" the chocolate. See instructions I followed here.

Pour the chocolate and let it set

By now, your chocolate is creamy.
As for the silicon, go slowly when pouring to reduce the amount of bubbles. You may even want to push a tiny bit at first into the nuts and crannies of your mould so that the details definitely come out fine (bubbles where the key features are, could really impact the look of the final result).

4. Final result

Once the chocolate has set, gently remove from the silicon, show it to get the effect it deserves and enjoy...

Here are some examples of the final result

Next steps?

So first, some lessons learnt from my first attempts include:

• use sellotape to stick the models to the base
• if 3D printing multiple models, it may be worth grouping as one piece (like a chocolate tablet) so everything keeps in place
• sand the 3D prints for a smoother finish
• use a spatula (or more generally proper utensils!)

Going forward, it would be interesting to:

• find food safe silicon compatible with resin and experiment with new shapes to allow for finer details (e.g. it is hard to print a logo on a small piece that would retain the correct level of details)
• try deeper chocolates shapes (the ones we are used to get from chocolate shop with more volume) as well as experiment with fillings such as praline, or crushed nuts/almonds etc...

In short, fun has only just began and please do not hesitate to share your creations below ...

Thanks to @fergusk for some of the tips mentioned above