Fiskars Craft Knife Cover

I really like the Fiskars version of the #11 XActo knife. It has a few flaws, but it's weighty, heavy duty, and works great for my larger hands. The real downside of it, is that the clear cap that comes with it is garbage. It flops around, who knew a blade cover could flop around, and it falls off with the slightest touch. This cap has a ridge inside that indexes into the trough below the blade holder, like the original, but holds tightly. I've included the Fusion 360 file to make your own changes.

Print this with ABS, ASA, or something that can take the flex/spring cycles this cap will endure. The cap uses the tension of the material and the ridge to make it exert pressure and stay on. If you use PLA, it will work for a little while, but the flexing of the cap open a closed as you take the knife in and out will eventually cause it to fail because it's just too brittle.