Enclosing magnets into a print 
this was only a test
I’ve done several things with trapped magnets, including an articulated MineCraft Steve, and a bottle opener that catches the cap. Lots of fun.
Did you stop the print part-way, then insert the magnet, then resume the print?
@Paul_Gross ​ no i used Prusa’s color print to edit the gCode and add a filament change command at the needed height so it stops and asks for a filament change, then you insert the magnet then trim the friendly little ball that formed on the tio of your filament and reinsert it and itll finish the filament change and go back to printing. I didnt know that blob would form so i just started it back up and it jammed my extruder and i had a heck of a fun time getting that out lol (not really)
My magnets jump out of their resting places and stick to my little heater cartridge when the head passes by. Maybe I need to use weaker magnets, or put a little sticky-tack on them when adding them to a print in progress?
@Tim_Visible I had the same problem, so I use more magnets at the outside of the print, choosing a convenient location so that they hold the entrapped magnet in place.
Interesting. That could help you make sure you get the polarity right, too. Thanks!
@Tim_Visible ​ i have the hole pretty tight so you really have to push the magnet in. That ensures it wont jump out as easily. The diameter of the magnet is 6mm i set the hole to 6.05mm
I simply superglued my magnets in mid print. No chance of jumping.
Lol