Simple folding utility blade that prints quickly (under ~1.5 hours total print time depending on settings). Locks in the open and closed position for safe usage and transport. Simple lever design makes closing it quick and easy. 

Requires two M3x12 screws, one M3x8 screw, three M3 nuts, and one utility blade. 

Choose either version of Handle A, one with a keyring hole and one without, and print with all the other parts as oriented in the files. The only part that may cause printing issues is the blade holder, enable brim if you don't have good bed adhesion. 

Printing the Handle A and B on a textured sheet gives a nice finish with improved grip, but not necessary. 

Assembly: 

Insert two M3 nuts into the recesses on the outside of Handle A. 

Insert one M3 nut into the recess of Blade Holder. Press it in until it lines up with screw hole. 

Put the Lever, Spring, and Blade Holder onto the respective shafts of Handle A. 

Align the holes in Handle B with the shafts of Handle A and secure with two M3x12 screws.

Insert the utility blade into the Blade Holder and secure using the M3x8 screw. Use the viewing window to help with alignment if needed. 

Done!

Note: If the lever fails to return to its resting position after being pressed, loosen the screw through the spring shaft until the lever freely returns to position. The screw through the blade holder shaft can be tightened down pretty good with no ill effects, the tighter it is the less wiggle the blade holder will have.