Introduction: Edible Chocolate Brain From MRI Scan

This instructable will show you how to create an edible chocolate brain from sliced data sourced from an MRI scan.

Our colleague at Inition, Andy Millns had his brain MRI scanned as part of a research project (he didn't say what into!) and we managed to sneak a copy (get your copy below!).

The main steps involved are:
- Converting sliced DICOM data into the STL file format (a 3D geometry format widely used for 3D printing)
- Editing that model to clean up
- 3D printing a solid model
- Producing a latex mould
- Finally casting the chocolate and eating (image of Andy eating his own brain above).

We've made the original DICOM files and the STL file available for download below under the Creative Commons Attribution License. If you like the project - we would be very happy if you voted for it in the Instructables 'Make it Real' challenge - the voting button is top right of this page.

Step 1: DICOM Data Import

First we need to convert the DICOM data from the MRI scan into 3D geometry.

We did this using InVesalius 3, an open source medical application (available for Windows and GNU Linux).

First, import your sliced DICOM image files into InVesalius. For highly detailed data you may need to limit the number of images that are used to generate the 3D model.

Invesalius Download Link;

Step 2: DICOM Data Model Export

Once InVesalius has calculated the model, you can adjust the settings to select only the brain. We did this by filtering out everything but fat tissue then adjusting the levels to select as much of the brain as possible.

Don't worry if other parts are selected - these can be removed later.

Once you are happy with your selection, save out as an STL file.

Step 3: Cleaning Data Using Meshlab

To clean the data you will need MeshLab, another open source appliation, primarily used for post-processing scan data.

Download Meshlab here:

In MeshLab you will be able to view and navigate your 3D model as well as select and delete unwanted data. Use the two selection tools and the selection options in the filter menu to do this.

Once you are happy with the data, perform a poisson reconstruction to reconstruct the surface of the model. This forms a waterproof mesh suitable for 3D printing. This tool can be found in the filter menu under remeshing, simplification and reconstruction.

The reconstructed mesh will appear as a separate model in the layer dialog. Select this mesh and save it out as an STL file.

Step 4: Cutting the Brain in Half

The waterproof STL brain model then needs to be taken into a CAD software to be cut in half. We used 3DS Max, however, you will be able to do this in any similar software including Blender, another free application.

We cut the model in half using the boolean tool to subtract a plane or thin cube from the model. Select and save out the two files separately as STL.

3DS max has an STL check tool in its modifier panel. It is a good idea to run this before saving out your model as it ensures your model is suitable for 3D printing. If your CAD package doesn't have this feature you can download MiniMagics, yet another free piece of software that identifies errors in STL files.

Step 5: 3D Printing

You should now have 3D printable data in the form of two STL files.

A wide variety of 3D printers are capable of making the models needed for the next stage. A low-cost bureau service like Shapeways is a good option. We also run a bureau printing service at Inition in London.

We 3D-printed our (well, Andy's) brain on our zPrinter 450 which uses a plaster-based composite material.

Step 6: Post Processing 3D Print

This next stage is specific to ZPrinters that use powder-based materials. Other 3D printing processes will vary but the idea is to end up with a model with physical strength and smooth finish suitable for creating a mould.

ZPrinter Part Finishing

The printed was was finished by brushing and de-powdering (as we do with all ZPrinter parts).

We then sealed the outer surface using multiple layers of epsom salt spray to create a hardened outer crust.

Step 7: Latex Mould

To make the latex mould we covered both halves of 3D printed brain in multiple layers of a food-safe latex. Make sure you wait for each layer to dry before adding the next. Depending on the model, anything from five to ten layers should be enough.

As soon as you are happy you have a thick enough layer of latex over your model, carefully peel it off. Wash out the inside.

Step 8: Melt Chocolate

Melt chocolate in a microwave or on top of a pot of boiling water. Pour the melted chocolate into the mould. It’s a good idea to use a brush or a teaspoon to push the chocolate right into the corners. Once the mould is full, put it in the fridge and leave it to cool for a few hours.

When you remove the chocolate from  the mould wear rubber gloves and run them under cold water first to avoid melting the chocolate.

Step 9: Eat!

Food for thought...

According to Andy, there's nothing quite like eating your own chocolate brain, but we'll have to take his word for that...

If you like the project, please vote for it in the 'Make It Real' challenge above. Thanks. We'd love to see any photos of your attempts (and chocolates most welcome).

Check out the video of the process below. If you're in the UK (or Australia) and interested in 3D printing, get in touch -

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First Prize in the
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