I had some problems breaking the support structure from the inner ball, so I brought it into blender, separated the inner and outer balls into separate meshes, and separated the inner ball from its support.
I then hollowed the support.
The original support is still in the blender file along with the hollowed support and the inner and outer balls, all in different layers for easy mix and match or additional editing. Also, just in case someone wants to print the parts separately (and, like, cheat by dropping the inner one into the other one after it is half printed), I will include STL files for both the two balls together with the hollow support, and the two separate balls.
meshball-hollow-support.stl | 451.7KB | |
meshball-inner.stl | 216.9KB | |
meshball-outer.stl | 216.9KB | |
MeshBalls_1.blend | 1.3MB |