Found on the 405th.com forum. This is Dancin_Fools's design for a Green Lantern Mask (although you may have to scale it up a little to make it a wearable size). This is a great costume piece and goes well with the GL ring that i posted a while back.
Get the Green lantern Mask here (where you'll also find a wearable Cyclops visor, a Batman cowl and loads of Iron Man armour) [link]
As always if you have any trouble accessing the website you could always send me a message and i will email you a copy.