Nice helmets!
I have been seriously looking into getting a printer, for myriad custom projects (STECK, STECK, STECK!), But the price is holding me back yet. (It's hard to be thrifty AND an early adapter...) Especially on the larger printers needed to make building parts.

My understanding is that other color input plastic is easily available. So, if you ever want to crank out helmets by the batch, you could create them, say, in grey. Is that right?
Have you already sanded the helmets in the pix you posted? I can see the tiny ridges on some of them, but they are VERY slight. I was expecting less resolution (?) from the examples I'd seen. Output objects online mostly looked like 90's era video game images, with lots of "bumps". If your prototypes are not sanded, I am very impressed with your printer's quality.
Very cool stuff. Keep on designing!
doug