Has anyone got a good way to cut lenses for waterhouse stops that they can share?

A circular saw would give a nice, clean cut but the blades all seem to be 3-4mm thick at least and I'm thinking the thinner the better. I'd guess the vibrations could also do some harm to the elements in barrels that don't have ways to unscrew and remove them.

A hand-saw would obviously give a thinner and safer cut, but it seems like it would be tricky to get the cut straight on a shiny, round metal barrel.

Thoughts?