I’ve been looking for a convenient way to carry a small compass on my keychain.

I have a Suunto Clipper and it’s good, but there’s no provision for keychain attachment.
I have a Brunton Whistle Compass, but it’s large and the plastic whistle broke.
The compasses made by Tru-Nord and Marbles have a classic design, but they’re expensive and aren’t liquid damped.
I’ve been thinking about the Sun Mini-Comp II and some Brunton models, but all the ones I’ve seen have a lot of unnecessary plastic housing around them.

So then I thought: Take the cap from an aluminum or brass capsule and glue inside (maybe with epoxy) a reliable button compass. (Dispose of the body of the capsule somehow.) Attach to keychain with a brass or titanium clip. You’d then have a button compass slightly recessed in a snug, protective metal housing.

The main problem, as I see it, is to get a good fit between compass and capsule cap.

Has anyone has tried something like this, or maybe could give another suggestion for a keychain compass?