A hinge system for an Iron Man helmet that should work with most helmets. Rather than trying to match the slope of any particular helmet, ball joints are used to fit whatever part of the helmet you stick it to. It's a little bulky, but could be a good starting out point for other, similar designs. It might be possible to take the same concept and re-build it with store bought hardware.

Designed to connect to 9g servo horns. Print 2x Servo Arms (1 mirrored) and 2x Arms (either "Arm" or "Medium Arm").

I used Tree Supports when printing.