I was inspired by calebjc's green helmet
to build my own. I suspect the parts on mine were easier to come by (bike store and wherever solar powered yard lights are on sale). Another addition on mine is that closing the buckle switches on the helmet.
I needed to attach a block to the bottom front of my headlight to raise it, on first draft it lit right in front of the front tire unless I looked at the sky. I had checked the aim at home, but had not thought about how your head is held differently on a bike with relatively low handle bars.