Oldtool
Nice device MrRick. The aspect of this that I like the most is the wooden hinge. I've got to try one of these hinges someday, when I finish my grandson's bookcase. 
I'm assuming the half twist lock on the back is via a small bolt with the head in the wooden knob. Correct?

Thank you very much Oldtool! The wooden hinge was exciting to do. It is every time I do it. But it's alot of work. There is no lock on the back but rather the side knobs themselves. They just tighten.  They are made with a dowel that's been tapped for a #10-32 thread. I then snipped off a piece of machine screw, CA glued about 1/4" of the end to be inserted and threaded in the tapped hole.

Here's a detail of the knob when I was making them. After they are made I chucked them up in my drill press and sanded.