It's  a box for cutter/ scalpel blades.

It can contain 6 blades.

IMPORTANT , files : 

•  the cover1 can contain 4 straight blades and 2 normal blades. BUT you can put straight blades in normal blades hole it will be just less stable. Straight blades hole are bigger thane others. 
• The cover 2 can contain 6 normal blades 

Print settings:

I recommand you to print the parts with a good résolution ( 0.15 ), without any support and with a 20% gyroid  infill.