the object you´ve uploaded to dropbox is a polysurface but this won’t help much as it is just one converted from a mesh using
_MeshToNurb. This command just creates more trouble as it does make the object less editable compared to the original tsplines object. Never use
I´ve used the fixed mesh (the inner one) from my first reply and offsetted each mesh part inward by 0.5, however this created intersecting faces which had to be fixed using commands like
_3DFace. Finally i´ve deleted and rebuild a few non manifold and intersecting mesh faces, to seperate the cutouts and create sharp edges i’ve used the command
To be honest, it quickly can get very time consuming to repair meshes in Rhino and finally obtain a watertight mesh which passes
_Check. If you purpose is rendering, the result might be enough, but for 3D printing the mesh would need further cleanup.
Help_cg.3dm (2.5 MB)