I ordered these butterfly clutch tack pins and jewelers epoxy from amazon.
In my design, I bored out a shallow hole on the back for the head of the pin to fit into and provide extra grab for the expoy. Then I just dipped the pinhead in epoxy and placed it in the cavity. I’m very happy with how it came out. I haven’t fully field-tested these yet to see if the epoxy holds throughout the day, but it feels pretty solid.
A tip on placement: do not center the pin on the back (especially if you’re using a heavy material like brass). When wearing it, the weight will pull it downward, making it look droopy. Instead, mount the pin post somewhere between the center and the top so it hangs naturally. I learned this the hard way with my first attempt.