How to glue balls to bolts. Place bolt on magnet, apply epoxy, put on ball. Ball is sucked to bolt center and is perfectly aligned. Rejoice.
Inspired!
Looks like someone has been taking apart hard drives.
Thx 4 the tip. 
Oooooo… nice.
Excellent idea
Lot of messing when you can buy them off the shelf, but kudos for your solution.
Thanks, where did you get that red plastic holder thing at the left side in the photo. You used it to hold 2 such ball-glued-items as well.
@Nigel_Dickinson bolted balls are expensive. These balls came from a dollar store magnetic toy.
@VCSekhar_Parepalli that red thing is printed.
Are you using hex headed bolts?
Yes.
I also forget to mention that I sandpaper the bolts and balls to get better adhesion.
So, what project are these for?
A delta printer.