Got bored one night and decided to be semi productive and make a few magnets for different things. 

Magnets are printed INSIDE the object, using 20x10x2mm magnets. Can be found easily on amazon. 
 

https://a.co/d/7DLZeI9  ← any like this will do 

Does not require alot of infill, too much will weigh down the magnet.

Always check your polarity before inserting magnets. 

Create a stop at the last layer before the space for magnets get covered.