You can print these in bulk (10 minutes to print a single but you could print multiples at once) and focus a class just on making charms for them.
A note about charms: using jump rings makes the bracelet easier to wear with the charms as demonstrated with the octopus vs the Pokeball and dinosaur. Plus you don't have to worry about the size of the plastic printed ring in Tinkercad too much. These are 9mm jump rings that come apart with simple pliers. Of course by having them loose, they will all dangle to the bottom but some 3D printed beads/spacers and jump ring size experimentation will do the trick. Although the PLA claims to be biodegradable who knows how long that would take. This is wonderful recycling project just in time for Earth Day.