The ThinWall plugin will be available for Rhino v5 only, starting with v5 WIPS released after 4/24/2009. Users are warned that it is a true Work In Progress. The interface has been left in its current lame state by the developer because he is only concerned with the geometry results at this time. All output from these commands should be checked for validity, as well as naked and nonmanifold edges.

This command operates on solids only. You pick on the surfaces to be removed and the result, when it works, should be a shelled polysurface. In the initial release, this is an old attempt that worked on some simple models. It has been replaced with code that is currently under development. It only shells inward, and has the limitation that any surface adjacent to a removed one must offset in a way that it intersects with the removed surface.

These can help when the high level command fails. You'll have to try them to see how they work.

Pick a surface or polysurface, a distance, and a direction (Inward is opposite the arrows that show if you call the Dir command). The result is the offsets of the surfaces of the polysurface trimmed to their intersections. If the input polysurface is not closed, and adjacent surfaces along the open border do not fully intersect when offset, their intersection is extended to the border. If adjacent surfaces offset away from each other, the gap is filled in with a circular blend. There is an option to join the results or not.

If you were to make a rolling ball fillet between a surface and a curve (see FilletSrfCrv below), this gives you the curve on the surface that is the edge of the fillet.

If you were to make a rolling ball fillet between two surfaces, this gives you the curves on the surfaces that are the edges of the fillet.

Pick a bunch of surfaces and polysurfaces. This puts them all into one, probably nonmanifold, polysurface with edges at the intersections.

This takes the nonmanifold mess created with MergePolysurfaces and finds all the closed manifold regions. Use it together with MergePolysurfaces to get a better version of CreateSolid.

Creates a rolling ball fillet surface between a surface and a curve.

Feel free to try whatever else you find in the plugin, but do so at your own risk.