This instructable will show you how to create three-dimensional forms based off of photographs, mill out a foam object from those digital forms, and use wax to create a physical representation of the "digital anatomy."
Step 1: MRI images to 3D object
Use "control point curve" to draw a line around the object you wish to make 3D, in my case it was my heart and aorta. (Figure 3) It is important to turn Osnaps off for this, so that the line will be on one plane and not snap elsewhere where you don't want it. Use the "patch" command to create a surface from the closed line, and then use "extrude surface" to create an extension that can hold volume. (Figure 4) Make sure that 'cap' is selected, so that the extruded ends are capped and the figure is solid.
Insert another image, with the same "picture frame" command. This image should be another view of the same object. For example, if the first image was of the front of the object, the second image should be of the side of the object. Rotate the second image 45 degrees. (Image 5)
Perform the same process on the second image: control point curve, patch, extrude surface. You now have two solid objects. (Image 6) Depending on where you place the second image, the tracing line may or may not be directly on the image. If it is not, the process works just as well. However, for patch to work correctly, make sure that the line is not curved through multiple coordinate planes.
Arrange these two objects so that they intersect one another. (Image 7)
Use "Boolean2Objects" and select 'intersection.' This should result in a three-dimensional object that is roughly the shape of your desired piece. (Image 8)