Hi Tim, STL format is generally not suitable for import into a CAD program like MoI.

STL format was not designed as a way to transfer design data at all, it's just a dump of triangles that was only ever meant to be consumed by the print slicer and not edited.

So it's not an easy process to do that, the data that you have is just fundamentally not the kind of data that MoI is set up to work on.

There is an STL import plugin here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=7046.5

But I don't recommend trying to do that - CAD models do not work well when having something like hundreds of thousands of little trimmed planes in them.

For STL editing you would be better off loading it into a polygon modeling program where at least the data matches what the program is designed to work on.

In a CAD program there is some overhead for each face, like there are 3D edge curves and also 2D edge curves in the parameter space of the surface. This allows to have an accurate model where something like a sphere is represented with just one precise surface but it's not an efficient way to store a hundred thousand triangles.

One method you could use for getting some data to begin the rebuilding process is to get it converted into .obj format and then use the OBJ to 3DM wireframe converter from here: http://moi3d.com/resources#Obj23dmWireframe_converter which can convert polygons in an .obj file into wireframe line segments in a .3dm file and you can then open up that wireframe in MoI.

- Michael