Here's how to make a low cost costume helmet using cardboard. Helmets are usually one of the hardest and most expensive parts to make for a cool Halloween costume so here's a simple method I use. The methods I describe can be used to make almost any kind of helmet but I'm showing how to make a Star Wars Boba Fett helmet as an example - I have an instructable for the rest of the Boba Fett costume here:
The templates provided are used by permission from The Wizard of Flight via the Dented Helmet- the definitive Boba Fett costume resource-thanks Alan! The templates are designed to be printed on 8.5" x 11" paper.
For more great scifi costuming templates check out SPC -there's a lot of fantastic patterns there!