I’m no watch maker, but it is good to be able to do some basic work, especially replacing crystals. So I recently got hold of this box:

A well used box 🙂  Inside are some very nicely made crystal and bezel fitting tools for ‘OR’ cases, i.e. ‘parawater’ :

Each tool comprises three pieces:

Instructions are included:

Fortunately for me, there are pictures as well as Japanese text: