Someone over on reddit thinks the sphere will fall apart without nuts on the outside holding the bolts in place.

Obviously they’re not an engineer, or perhaps they missed the fact that all the holes would be threaded. We would of course have some kind of locking washer in place to grip the bolt tightly and with a ‘belts and braces’ approach 1 drop of good old locktite screw thread glue is always a good idea.

Have a picture:

Screenshot 2014-08-01 05.40.36

I couldn’t find a bolt with a shorter thread length than a 6mm  on a 6mm bolt, but this is only a proof of concept.