My kids loved this model (https://www.thingiverse.com/thing:4626168), but wanted it to stay in one piece - so I added a hinge to the backpack. Part 2 needs to be printed with supports for the hinge only. Part one does not need supports.
Use some 1.75mm filament for the hinge. (This works well on my printer, but if it's too loose or too tight add a comment and I'll upload some more versions).
Printer Brand:
Prusa
Printer:
I3 MK3S
Rafts:
No
Supports:
Yes
Resolution:
0.3
Infill:
15%
Copper