Pin Back
thingiverse
Replacement pin back that is based on the rubber PVC backs you can find online. In my experience, these work much better than the metal butterfly clasps. I used TPU and they work great, I recommend printing a few of them sequentially instead of all at once due to stringing with TPU.
Download Model from thingiverse
With this file you will be able to print Pin Back with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Pin Back.