This is a foldable ear saver that can be put in a pocket to always carry it with you. It has several hooks to adapt to the various types of masks on the market, and to the various lengths of the rubber bands. The protruding hooks are more comfortable than the flat ones, because they are easier to find by touch while wearing the face mask.
The piece can be printed in rigid materials such as PLA or ABS, which are easy to 3D print. The piece consists of 2 separate halves, but they must be printed at the same time. You just have to load the STL into the slicer and print at 0.2mm resolution.