Special folding hinges for case-rap (custom version)

Edit: I'm slowly documenting new versions and updates of my custom printer here: http://www.reprap.org/wiki/Valentia

Screws, washers and nuts are all M4, except for the screws that fix the hinges to the wood, which are 3-3.5mm diameter 16-20mm long screws for wood.
Make sure dimension marked as "X" in one of the pictures doesn't exceed 200mm, in my case's case X=102mm.
This is for my ongoing version of jlguil's case-rap, where I want to test some experimental designs trying to reduce weight