My daughter wanted a smaller version of the pony popper she bought in a store. It was too big and wouldn't stay in place on her pony tail.

I designed this one to use some salvaged Neodymium magnets to clamp itself closed instead of the clasp the original used.

You will need to make adjustments to the design so the cavity the magnets slide into match your magnet dimensions. My magnets were .595"x.235"x.115". I made the cavity just small enough that the magnets had to be pressed into them so I don't need any glue. You also need to pay attention to the amount of filament that ends up between the magnets when the clip is closed. I've designed this one with 0.062"/1.6mm (0.031"x2/0.8mmx2) separation when closed. More than that and your magnets loose their clamping force, less than that and my printer has trouble maintaining the walls consistently. The oval openings are simply to remove material from between the magnets.

The same goes for the pin you choose to use as the hinge pin. The piece I'm using is 0.085" diameter and it too is pressed in so it doesn't need glue.

This will be easy to scale but you will need to keep magnet and hinge pin dimensions constant as well as the magnet separation distance for reasons mentioned above.

I've uploaded files for the two halves separately as well as an assembly of the two if you want to print in place. The hinge gaps are drawn to 0.009" (.22mm),