Rapid Prototyping

I need to generate my architectures in an actual material for two reasons 1) check my FEA with actual mechanical compression data and 2) In the third part I will eventually need to make my architectures with polymers that can sustain cell growth to test for bone regeneration purposes.

I make most of my shapes with lovely, lovely Rhino. The pictures here correspond to a series of cutplane, mirror, array, and patch functions that I use to generate the complete scaffold, shown in 11. To make a mold of this, I cutplane the top part of one architecture, surround the entire thing with a cylinder, invert the normals and join.
I have designed the mold in two ways in the past which has worked. The first is a simple cup mold that can hold a volume of material above the void space. Then I centrifuge the material in or pull a vacuum. The second type of mold is and injection mold, shown here for a novel bone anchor that I designed and built. On the right, the bone anchor in ProtoBuild, middle is injection mold, left is finished bone anchor cast in poly(propylene fumarate) a biomaterial we use. Closeups of the mold and the cast part are below.
Notice the white material on the surface of the bone anchor. This is from dissolving the green material in organic solvents. I dissolved it with Acetone which seems to have a chemical reaction with the green material. I have created a solvent selection process to decide which solvent to use based on what my casting material dissolves in. High absorption means lots of particulate matter and not a clean dissolve of the green material. DMSO is the best, and Acetone is the fastest and most corrosive.