This is a safety box cutter I designed in Fusion 360. Printed in PLA. The cutter in pictures is printed at 85% scale. Designed for easy 3D printing.

You can use either the pointed tip or cutting groove depending what kind of packet you're cutting. Pointed tip is generally for small packets and cutting corners open, V-groove is for long straight cuts. For sharper V-groove tip, you can use cutting pliers to cut it (like in the picture).

It's also possible to glue metal blade on the back side of the V-groove if you want it to remain sharp for longer time.