Lately I've been thinking about some features it would be great to have in AC3D to help in preparing models for 3D printing:

- Better extrude by normal. I roughed some math in pseudo code on this thread that keeps the new surface parallel to the old surface so the extrusion distance is more exact.

- Water tight test. I believe ensuring every edge is shared by exactly two edges is a simple test of water tightness. Perhaps the plug-in could change leaky surfaces to a specified material. A brief look through the SDK makes me think this is already 95% done in AC3D.

- Consistent normals. Once we've achieved every edge being shared by exactly (one or) two vertexes, I think if we test the edges to ensure one goes from V0->V1 and the other goes from V1->V0 we can know the normals are consistent.

I am hoping to gain some free time in the near future to work on these things. If someone would like to step-up to mentor my on the internals of AC3D, that would be great.

There are also some things I don't have an idea how to solve:

- Self-intersection test. Testing to make sure no surfaces intersect each other.

- Wall thickness test. The 3D print service I've been using has minimum required wall thicknesses.

- Object volume. The 3D print service I've been using also charges by the cubic centimeter, so it would be nice to figure out how much a model would cost before I upload it.