This is a simple way to add a hinge to your leftover Ferrero boxes. No Hardware required!
 

-- There is a PDF with instructions included in the files!  --

If you want the boxes to lock, you can download the lock STL, but you will need two M3x10mm screws and two locking M3 nuts.

You can see how the lock works in the second photo, but you'll have to align the holes yourself. If people request it, I'll make an aligner for drilling the lock holes.

Info:
Time to print: ~ 35m

Material: Printed in PLA, but will probably work for any material.