X-Acto Knife Cap/Cover/Sheath

I wasn't happy with the blade cap that comes with the popular X-Acto knife (Z-series #1, 8mm diameter handle) - it kept falling off and was flimsy, it seemed like a minor stabbing waiting to happen, so I made this design.

The .3MF file has three examples, with .1, .2, and .3 MM of clearance between the knurled part of the knife handle and the inner wall of the cap. You can just print all three (1H35M on standard Prusa settings and .4mm nozzle) at once and see what level of grip you want with yours. Alternatively, I've uploaded the Fusion 360 file as well for those who want to alter it further - see the custom parameter for clearance.

The cap is printed upright along the Z axis to keep the ID nice and circular. Make sure that you have good bed adhesion and plenty of brim as the part is fairly tall relative to diameter.

Just make sure to approximately align the blade of the knife parallel with the flat sides of the cap when inserting the cap onto the knife. It doesn't have to be perfect but given the dimensions of the blade itself, an omnidirectional cap isn't really possible without crashing into the blade.