I had to buy a Toyo TC-17VV glass cutter in order to cut a small piece of glass.  After I was done, I was left with an unprotected cutting tool!  I took some quick measurements, and did some test-prints until i had a cap that fit.

The cap is designed to self-retain on the set-screw installed in all TC-17VV cutter heads, so no additional fastening is necessary.  The cap can be pushed on or pulled off with ease.

The fit isn't super snug, and I honestly didn't confirm i had the angles right, but i think that's fine- it's just a cap, and it fits as snug as I'd expect it to.   TIP: If you disagree, just use the slicer scaling option and make it bigger (110%) or smaller (90%) or whatever, and try again!

It's a fast print, so you won't waste too much time iterating. 

Will it work on other cutter heads?  Maybe! i honestly don't know, but the windows probably line up with the other head labels, and if you're lucky maybe it'll just fit as is!