Introduction: Chocolate Casting Using 123d Catch and a 3d Printer

About: Making things is what I do!

Grech. The name is universally known at my high school. Mr. Grech is a history teacher and the best of his kind. He is wonderfully exuberant and makes every class extremely fun. Obviously, his popularity ensues lots of strange/clever gifts for his birthday and the holidays. However, I have outwitted them all with this chocolate surprise! Using a 3d printer, 123d catch, and liquid silicone I have made an entire set of chocolate heads identical to his! Read this instructable for a comprehensive guide on how to make personalized chocolate busts!

How It's Done

The process I used to make this chocolate model was very simple. It works by 3d printing a model of your subject's head, and then creating a mold of it with liquid rubber. After this, it is the simple matter of pouring chocolate in the mold and freezing it! Keep reading for in depth instructions and remember to vote for this instructable in the Baking and Homemade gifts, and 3d Printing contests!

I learned a lot about creating molds from this tutorial by geeksmithing. After reading his post, I then had the idea to incorporate 3d printing and 3d scanning into the process as well! Thanks for all your hard work, geeksmithing!!

Step 1: Materials/Tools

- Mold-making Chocolate (You can use Hershey's chocolate if you're in a pinch, but it will melt more quickly.)

- Liquid Silicone (rubber)

- Computer with 123d Catch, 123d Design, and Meshmixer installed

- 3d Printer (Or you can use an online 3d printing service like Shapeways.)

- A willing participant

- A mug

- A container for the mold to solidify in. A normal paper cup works well.

- A couple paper cups to mix the liquid silicone in.

Step 2: Scan the Subject's Head With 123d Catch

In order to complete this project you must obtain a 3d model of your subject. The easiest and most cost-effective way to do this is by utilizing the technique of photogrammetry. Photogrammetry means generating a three dimensional point cloud by a set of photographs. Follow these steps to perform it:

1. Ask the subject (Mr. Grech in my case) to stand still for the next couple minutes. Be aware this may take some convincing.

2. Open up your smartphone camera then take 30-50 photos of every side of the subject's head. Make sure to capture crevices such as below the chin. The quality of your model/chocolate depends on the resolution and quantity of these images.

3. Thank your subject for being so stationary. Tell him/her to stretch their neck.

4. Email all the pictures to yourself from your phone.

5. Open your email on a laptop and drag the images onto your desktop or in a desired folder.

6. Open 123d Catch and upload the photographs. Then press create. Be patient, complex scans can take up to 5 hours to complete.

7. Next press the Edit/Download button, and select Download 3d Models.

8. Again press Download Models in the next window. Once the .zip file has finished installing, you are ready for the next step!

Step 3: Prepare the Model for Finishing in 123d Design

Right now your 3d model isn't yet an .stl, which means it cannot be edited or modified in Meshmixer. To convert it we simply need to export the head out of 123d Design.

1. Open 123d design.

2. Select Import then 3d Model.

3. Choose the file you downloaded in the previous step.

4. Go to Export 3d Model and select STL.

5. Name the file and keep note of where it saves to as we'll need to use it in the next step!

Step 4: Tweak and Edit the Bust in Meshmixer

This is definitely the most difficult step. Depending on the quality of your model and your previous experience in 3d modeling this may take a long time or be relatively brief. The process will be unique for every scan, but I'll try to document it as well as possible.

1. Open Meshmixer.

2. The first thing you should do is isolate the head from its surroundings. Go to Edit then Plane Cut to chop off the unwanted sections. Don't panic if all you see is a giant mess of bumpy ground. Chances are your model is somewhere, still intact, but very tiny. This happens when a lot of the background in the photographs is a similar color to the subject's head/shirt/appearance.

3. Almost everything else will be done with the Sculpt tool. When you have this tool enabled, and click, it will flatten out the surface of the model. Fix the imperfections and edit the face as you like with the sculpt tool until you're satisfied.

4. Go to Export then select STL. Save the file to an easily accessible location.

Step 5: 3d Print the Bust!

The 3d print should be fairly simple as long as the bottom of your model is entirely flat. Make sure to print it at .1mm resolution or lower if you want a good amount of detail to be visible. You can see my exact settings in the picture above!

Step 6: Create a Silicone Mold of the 3d Print

This is one of the most difficult steps. Follow along and remember the process will be a little different for everyone.

1. Super glue the bust to the bottom of your molding enclosure face up.

2. Take a paper cup and pour part A and part B into it. Fill up the cup about 1/3 of the way, (or whatever looks right to you.) The ratio of each should be about 1:1, but it doesn't have to be perfect.

3. Mix the silicone together thoroughly with a utensil. The result should be a dark purple paste.

4. Pour/scoop the paste into the mold container. Fill it up to the brim so there is no chance of the nose poking through the top.

5. Let the mold cure and solidify for four to five hours. It is easiest to complete this step in the evening and then leave it out overnight! You should be left with a rubbery, bouncy, soft material.

6. After the rubber solidifies, you need to get the mold out of the container. This can prove rather frustrating if you're using something completely solid like a copper pipe cap. I ended up using a hammer to hit the bottom, and eventually the mold just popped out.

7. Inspect the rubber and make sure there are no obvious holes or ruptures.

Step 7: Pour the Chocolate Into the Mold

As I mentioned earlier, I recommend a ceramic chocolate melting pot, but a mug will do just fine for now.

1. Dump a good portion of your chocolate into your mug/pot and place it in your microwave oven. Microwave for thirty seconds, stir it up a little, microwave it for thirty seconds, stir it up a little, etc. until the consistency is uniformly silky smooth. Make sure there are no visible globs or chunks floating around.

2. Pour the chocolate into your mold and flatten out the top with a knife.

3. Place the whole thing inside a freezer for ten minutes. Then transfer it to the fridge for another ten to thirty minutes until you're satisfied with the consistency. The reason for not leaving it in the freezer too long is so the chocolate does not become too brittle and brake when you remove the head.

Step 8: Uncover the Chocolate and Finish It Up!

Be very careful when removing the chocolate! Place both thumbs on either side of the mold and gently pull apart until the bust becomes removed enough to gently pull out. Depending on what type of chocolate you used it may melt fast so work quickly! After the chocolate is done, experiment with different types of presentations and displays for the finished product. Eventually, I plan to make a set of Mr. Grech heads and place them all in a pretty wrapped box!

To Conclude

Throughout this project I made a lot of mistakes and learned a lot about casting in general! For example, I should have used a bendable molding container as this would have made it much easier to remove the silicone mold. I think Mr. Grech will be very surprised and grateful when he receives the chocolates!

I would really appreciate it if you left a comment or gave me vote! Thanks!

P.S. If you go to my school and know who Mr. Grech is, don't tell him about this!!


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