This is a modified version of the Prusa face shield. I wasn't able to source button-hole elastic initially so I made this to work with flat elastic. This could also work with strips of fabric, ribbon, or webbing.

1. Push on the flexible tab to create a larger gap for your elastic (or other fastener) to pass through.

2. Pass the elastic through the teeth from the inside of the headband.

3. You can tighten the headband by pulling on the excess elastic from the outside of the headband.

4. To loosen the headband, pull on the elastic from the inside of the headband. You may need to press on the flexible tab.

ATTENTION: THIS REQURES SUPPORTS FOR THE TENSION LOCKS TO BRIDGE PROPPERLY. You can add supports everywhere but this is harder to clean up. I recomend using support enforcers. These are easy to add in PrusaSlicer. You only need about 2mm of support material near the teeth on the bottom of the tension tab for the bridging to be successful. See Documentation tab for a screenshot of where to put support enforcers.