this is for a set of cufflinks for a French cuff dress shirt. I recently 3D printed a Tie and wanted a set of cufflinks to match. I retrofitted this "filament keychain" to be a cufflink. I recommend printing the filament in a different color than the one you use to print the reel so it looks more realistic.

you may need to glue the pin into the real to keep it from slipping out. HOWEVER, I have uploaded a slightly larger pin for a snug fit that you can press in. For me, it will come out with a bit of twisting so it's not permanent but at least you won't need glue.