Interesting thread.
Is
this the kind of magnetite you're talking about? If so, it's clearly available cheap in small chunks-enough for an effort at making an example.
Are there any practical ways of shaping magnetite personally? Also, having seen the example of the 'notched' spheres you posted, how important is it to maintain the integrity of a perfect sphere 'underneath' the notches as it were? I imagine that part would be a little tricky without machinery.
As this thread is now over a year old-how are those schematics and videos coming?