The Most Comfortable Utility Knife In The World

I based this on a utility knife that my dad kept at his workbench when I was growing up. Whenever I used it for projects, I remember it being fantastically comfortable and ergonomic. I never took note of the brand, and when I started buying tools myself I couldn't find a knife that fit quite as well in the hand as that one - so I designed a replica as best as I could for 3d printing. 

The bottom unscrews and stores some spare blades. The tolerance on the threads might be a little tight depending on your printer and your filament - after printing, work the threads together back and forth, advancing very slowly until the cap bottoms out. If you have plastic-safe lubricant like PPFAE or dielectric grease it might help to apply a very small amount as you break in the threads.

Requires:

• M3x7 or M3x8 screws, 2x
• M3 nuts, 2x (5.5x2mm outer)
• Standard utility knife blade

Print with at least three walls. I also recommend printing with 100% infill for the feel.

The nuts press fit in, and the screws go through the slots in the blade to lock it in place. Do not overtighten, if you overtighten you can easily split the print. Tighten until snug.

This model prints without supports if you orient the flat surfaces between the handle and the cap against the build plate. The 3mf file is already oriented this way. You may need to split the .obj model into parts depending on your slicer software.