Replacement mallet head with magnets

I purchased a hobby/watch hammer from Harbor Freight.  I know I will eventually want to replace the striking surfaces of the hammer, so I measured and made a few PETG replacement slugs.

I have a few magnets that I've marked + and - to identify poles.  Finding those specific magnets is a pain sometimes.  Also, I fear having the markings rubbed off at some point in time.  To solve this, I modified the first slug I made to have an 8mm magnet inserted into it.  The striking surface is .6mm (3 layers) so there is plenty of flux exposure.  I made a plug to back up the magnet so it wouldn't go anywhere with any hammer strikes.  Since I wanted to be able to push magnets into pockets in either orientation, I printed another set in a different color and set another magnet into it.  After putting it all together, I have a red end and black end that can hold magnets with opposite poles facing out for easy insertion and pole identification.  If I need a different striking surface, I can always re-install either the acetal or brass slug when necessary.  The hammer handle gives a great grip for pushing magnets into tight pockets and will keep magnets if the pocket is too loose so you won't necessarily drop it.