The Crown of Bethmoora from Hellboy 2.
You'll need to print two copies of the sides and one copy of the file labelled "Front & Back". If you're going to wear it I'd suggest sticking the pieces onto a strip of card or something so it can flex and hinge. For display you can either glue the pieces as they are or pin them like I did. You may need to tweak the size to fit.
I couldn't get the front piece to slice correctly in RepG, had to use Simplify3D to get that working.
Full instructions can be found on my blog which is linked through my profile.
Good luck, and enjoy :)