Original work: https://www.printables.com/model/124050-clicky-changeable-clothing-buttons

I adapted this design to have a complete flat surface on the outside. 

As the 2 parts click together you can use it to use 1 part inside the fabric and the other on the outside to patch a small hole.

In my case I made it to fit a jacket where I lost a ventilation hole. (see extra picture)

The bottom part also has holes ready to sew it in place if needed.