Each of these models is a single-gauge wire stripper, customized for both wire gauge and strip length. It's entirely plastic (no metal parts) and print-in-place.
To use:
Here it is in action. You can see that it takes a bit of effort, but gives a decent result. This one is printed in PLA at 0.2mm layer height. I think one made from ABS or ASA and printed at a smaller layer height (at least for the first few layers) would be more durable and cut better.
Caveat: I've only tried the 22AWG version. Not sure about the viability of the others.
I've included OpenSCAD source in case you'd like to customize it.
The author marked this model as their own original creation.