This is a larger version of my earlier design.

Modeled in Fusion 360, printed "flat" in PLA with 80% infill it weighs just 27 g.

The dimensions are ~124×124×41 mm.

You will need a needle to keep it in place.

The old version successfully survived Feuerzone in Vienna on my wife's head, the new (larger) version is being tested "in real life" by two nice LIFAD members.

Do not print it in the orientation suggested by Bean Overlord! Print it laying flat (parallel to the buildplate) instead.