That’s got “make me” written on it in the biggest way - looks like a
fairly simple, straightforward tool to make - a divider and scribe
combination, with heat treated ends. I believe it was made out of
flat stock, with the scribe end slightly tapered and then twisted
clockwise on one half, and the other half counterclockwise. Then,
stock was removed to help round and complete the taper.
The divider is a second piece simply riveted (looks like a washer
may have been used as well) on to the first. Either cut out from
plate in the curved shape, or perhaps forged hot to shape. Ends
tapered to a point.
Not sure how big it is because the photo does not show anything else
for scale, but if it is a hand tool, you should be able to
accomplish this nicely with some oil hardening tool steel (I like
O1) and a suitable quenching medium (olive oil works) and basic
metalsmithing tools. It can pay to do a bit of research here - all
steels have somewhat different heat treating schedules, and an
improperly heat treated tool can be very dangerous - especially if
it is one struck by a hammer.
Toolmaking can be incredibly free and liberating - give it a try!
For reference, check out Weyger’s blacksmithing books, and
McCreight’s knifemaking book - both have chapters that speak to heat
the tool in question:
Chris Ploof Studio