I have a bunch of BuckyBalls and I wanted to print this for a long time. I had a short print window available the other night so I cranked out 3 for a test. It's really tough to get the magnets in but the spin well once you do so I guess they're really secure in there. I found it was easiest to put the magnet on a surface and press the socket down over it. To save my thumb a bit I used a folded up napkin for padding.