One of my hangar neighbors was cleaning out an old desk, used by a now 10 years deceased old school aircraft mechanic, and among the Pratt & Whitney radial engine tools and other debris was a couple of these things:







I'm thinking some sort of crimping tool?

I'm using one of them as a 'stop' for my spindle holding tool.



The magnet holds the tool in place, the "tool" limits rotation of the spindle on My Emco-Meier Mill while changing tooling.