This is a simple design for cufflinks which uses a threaded connection on the cap to attach two sides together. This should be a bit stronger than the typical hinge/hook design. 

I have made a simple button design, and a gear design. You can interchange the parts as you like. Should be pretty simple to add a custom design as a remix if you'd like, as well. 

Parts can be printed in the given orientation without supports. 

It's a fast print, so I recommend a slightly lower (0.16) layer height just to give better strength, and more accurate threads/overhangs. 0.2mm height works too though. 

The button cap has been designed with a small bridge, which hides the threaded piece of the cufflink. I have attempted to design it to make this bridging as easy as possible, and it prints without any issues for me. However, if you have poor bridging, it's possible that this part could give some trouble. 

By the way, make sure you can unscrew them easily before you put both of them on! Don't wanna get locked in your shirt, haha. 

I tried printing them in PETG, but I found that it was a little too flexible, and the threads would grip extremely tight once it was screwed in, so I couldn't unscrew it without breaking it. So, I guess PLA is ideal for this part.