Clip for keeping bags sealed or add a magnet to hold small items on a fridge. Design based on popular Bongo Cat meme.
For good quality teeth at the pinching end I recommend orienting the object on it's side so that the serrations are vertical.
Spring I used was an OpenBuilds timing belt tensioner but any torsion spring of similar size should work.
Small finishing brad nails were used for the hinges; about 16mm in length and 1.5mm in diameter.
Optionally a magnet can by hot-glued or otherwise affixed to the back.