For some reason, my adivsor Ellen really wanted someone to make a heart out of LEGOs. She bought a bunch of random red and blue pieces and assigned the project to some undergrads. After a series of failed attempts in reconstructing a 3D geometry from a 2D picture, the project was dropped.
After I had finished a research project, it suddenly occured to me that building objects in the game, Minecraft, is similar to building objects with LEGOs. Thus, I set about to look into how people built these magnificent renditions of Star Wars Destroyers and such in Minecraft. Fortunately, it turns out that there are several programs, Voxelizers, that can take meshes and convert them into voxels. I used the voxelizer, binvox, to generate appropriate voxel representations of a MRI patient-specific mesh using the lowest number of slices necessary to represent the shape of the heart accurately (I am lazy.).
Afterwards, viewvox was used as a "blueprint" for building the heart. As the mesh is a surface mesh, the voxelizer only provides a blueprint for creating the outer shell. In viewvox, one can bring up translucent layers of the previous and next layers. This is helpful in determining how to place the LEGO bricks appropriately. Another difficulty is that Ellen had merely ordered an arbitrary number of 2x2, 4x1, 8x2, 4x2, and 2x1 LEGO blocks. This then became a resource optimization problem as I had to make sure I had enough blocks of a particular color to build the mesh. However, I was too lazy to LEGO CAD (this exists) the whole mesh, and decided to instead play it by ear. The previous failed attempts from undergrads had resulted in throwing all the different types of LEGO pieces together in a box, since this is how one usually plays with LEGOs. However, this would also mkae it difficult to keep track of the amount of blocks that would be left for a particular type, so I had to spend time sorting all the different LEGO bricks into separate bags by size.
After 10 hours and a pair of really sore thumbs (Building stuff with legos is hard work!), what you see above is the result of an engineered to-scale version of a patient specific heart made out of LEGOs.