I use several types of tweezer for my electronics work, and the supplied caps eventually wear out due to how sharp the tweezers are.

In the pictures, the caps are shown on size 3C and 2A tweezers, which are my most common use ones - I've actually used the same caps now on all of my tweezers and they all fit nicely.

I printed them using Taulman 645 industrial nylon, at a 0.2mm layer height, which is immensely strong and tear resistant, so I'm hoping I don't need to replace them again anytime soon.

https://sites.google.com/site/321soldersucker/home/random-ramblings/taluman645test-tweezercaps

I got a pair of bent nose tweezers which the original caps don't sit well on, so I've added a new cap specifically for those.