Harbor Freight Hard Hat Insert Adapter

This adapter takes the insert from an $11 Harbor Freight Hard Hat and can be customized to provide a stable mounting point for a helmet or other head mounted design. Image shows example screw holes and mounting arms for a large helmet, the file is just the band so you can customize it to fit your helmet.

Designed for this specific Hard Hat Insert, but likely compatible with similar models (untested) https://www.harborfreight.com/ratcheting-hard-hat-56672.html