In this project, I will try and guide through the different steps to make your own custom chocolates, thanks to 3D printing.
This is a fairly easy and forgiving project, and I'll try and include different alternatives for each step depending on your preferences or the resources that you have available, but feel free to ask any question that you have in the comments !
Step 1: Designing Your Object
The first thing that you'll want to do is to design the object that you want to make in chocolate. In my case, I wanted to make chocolate squares with the logo of my employer to give out as Christmas presents.
I used Fusion 360 to model the chocolate because it allows you to define and change some parameters (size of each square, squares per row, etc.)
The first thing I did was to create a sketch and draw a rectangle with the dimensions I wanted my chocolate square to be. I then created a new component and while inside that component, I extruded the rectangle by 6.5mm
I then added a 2 mm chamfer around the edge of the square, and then drew another smaller square on top of the first one and extruded it by - 2 mm (the negative amount makes it a "cut" operation). Once again, I added a chamfer to that newly created edge so that I had my working surface ready.
I then imported the logo (import SVG) and placed it roughly at the center of the square. I extruded it by 2 mm and my chocolate square was almost ready ! Well in 3D at least.
I created tiled copies of this square using the pattern operation, and I then added an extruded rectangle at the bottom so that every square was now joined (notice the change of color) so that I now had a chocolate bar
Alternative option : If you're not comfortable with Fusion 360, Tinkercad will allow you to do almost every action listed in this step except for the pattern, but you can just copy and paste the square to make it work
Step 2: 3D Printing It
The next step for me was to 3D print the chocolate bar. Since I don't own a 3D printer, I ordered a print on Shapeways
Step 3: Making the Mold
Once I had the 3D printed bar, the next step was to create the mold. I've done it quite a few ways, but the easiest one in my opinion is to use foam paper : Score (but don't cut) the four sides of that rectangle so that the foam part is cut but the last layer of paper still hold the two pieces together (see the second picture). Once you've done that with each side, you can then tape them together to get a box for you to use. Given the fact that the silicon mix is pretty liquid, you'll want this to be as watertight as possible: what I did was to use a glue gun to seal all the internal and external edges of the box, so that the liquid would not spill.
Once the box was ready, I glued the chocolate bar to the bottom of it (again, using hot glue) and proceeded to make the silicon mix. One last thing I did was to put a bit of oil (olive oil) on the 3D printed bar and the sides of the box so that it would be easier to remove afterwards.
The silicon mix I used is called RTV 3428 by Esprit composite, and is safe to use for all food applications. You have to mix the two parts in a 10:1 ratio (although it is fairly forgiving on that part). Once the silicon was ready, I poured it inside the mold, starting by the little details on the logo. I tried to obtain a 1,5 cm layer on top of the object to keep the same margin all around the mold.
This silicon has a 16 hour curing time but this is at 20°C so one night in a heated apartment was enough for it to fully dry.
The next day, I unglued the foam paper from the silicon pretty easily. As you can see, the 3D chocolate bar unglued itself during the night and began floating towards the surface but luckily, the silicon must have been already a bit harder by then.
The mold is now ready !
Step 4: Temper Your Chocolate
I don't have many pictures for that step but fortunately, tempering chocolate is fairly well documented. Whatever the process you're following, the idea is to melt the chocolate to a certain point (t1), bring it to a lower temperature (t2) and finally heat it again and bring it to a temperature (t3) that is between t1 and t2 and that will be your working temperature. t1, t2 and t3 depend on the kind of chocolate you're using (black, milk or white).
A bit of advice
I first tried to temper the chocolate the "right way", by changing the temperature using my cooking robot. Although this did produce some chocolate that was tempered enough to have the right consistency (solid and easy to break), the melted chocolate itself was really thick, so it didn't go in the little crevices of the mold, as you can see in the picture.
My recommendation is therefore to use the easy method : cocoa butter flakes ! You can get those pretty easily and all you have to do is add a certain amount to your chocolate while tempering it (depending on how much chocolate you have) and it makes the process pretty much foolproof !
It also helps to use some good chocolate - I used Barry's couverture chocolate, it comes in little portions that make it easier to measure and each batch will give you the precise temperatures t1 t2 and t3 to temper that specific kind of chocolate
As you can see on the pictures, even though the chocolate was properly tempered, the surface is still not as shiny as with another, commercial mold. This is because we're using a 3D printed object as our base and the surface will never completely smooth/shiny. I haven't tried polishing the print more but I think some kind of varnish would work best, applied on the object before making the mold. I just struggled to find something that would be food safe (I tried with caramel and that was clearly not a good idea) so I made peace with my non shiny chocolates.
Although practical, the cooking chef is not necessary - you can use the double boiler method to melt your chocolate before adding the cocoa butter flakes. If you happen to own a sous vide/precision cooking circulator, you can also melt the chocolate that way - just be careful not to add water to it, as it will pretty much ruin your whole batch.
Step 5: Package It or Eat It Right Away !
Your chocolate is now ready to eat !
The box that you see in the picture was made using templatemaker.nl , an awesome website that allows you to generate templates for all kinds of boxes ! This specific one is a regular "box with lid" and its "custom insert" : laser cutting the boxes is of course easier, but you can also print and cut them by hand.
Thanks for reading and feel free to ask your questions in the comments !