HEre's where my experimentation has gotten me:
I've got a space angel helmet in progress that's going very well using the following technique:
-baseball cap, cut off the brim
-using this posable wire mesh I found at an art store (Activ-wire) build the armature and pinned it on
-did all the wiring and LEDs at this point
-secured it with hot glue gun
-stiffened everything by laying gauze saturated with premixed wallpaper paste
and next I"ll do a thin layer of celluclay paper mache, because that's well sculptable and sandable to get the detailing and a smooth finish
and last but not least paint it.
The past, mesh and gauze have added some weigh, but its still significantly lighter than your average hard hat, including the batteries. And since its a baseball hat it fits my head well. No straps will be needed.
Ok it hasn't been really fast, I figure I've got about 6-8 hours into it at this point, with probably 4 more to go, not including drying time, but it will be awesome. And then I'm going to make a similar one for my wife, but hers will probably have blue LEDs instead of green. Awesomeness!
I wonder if I could just did the fabric of the cap into the wallpaper goo and save the step of the gauze next time...
thanks everyone! If you see me on the playa, it's silver helmet with cheek protectors and widows peak, two backward sweeping spikes, and 4 green LEDs going in a line from third eye back to tip of top spike.
My God, it's full of Stars!