This is a a fast and easy 3d printable box cutter knife for 18mm blades.
Use at your own risk!
I printed it with PETG (30% infill for the grip, 40% infill for the bladeholder), ASA might be a better alternative but PETG works for me too.
You need 6 screws M2 10-12mm long to screw the parts together.
The author hasn't provided the model origin yet.