Saying non credible af here, but in theory one could add a upwards facing shotgun shells on top of the helmet, triggered by a Camera/proximity sensor if it detects a drone/falling grande. Maybe add a gyroscope to check if the helmet is actually facing upwards before triggering. All in all unit cost could be below 250$
- 6x 12 gauge shells with bird shot
- Raspberry pi type controller
- USB cam
- Laser distance sensor
- gyroscope
- servo trigger
The real deal use radar/lidar sensors, so you can replace the whole sensor suite with 4 90-degree sensors facing upwards with the added benefit of being able to track not just range but speed and trajectory.
Slap the computer on the back of the helmet, and it’ll even work as a counterweight for the night vision goggles!