Silverlite. An aluminium and polypropylene sandwich-very light and rigid, but with a very special property. We can rout a hinge. This achieves an extraordinary accurate, tiny hinge that is integral to the cover. Being so special is not cheap, but for something special, it is very special indeed.
Silverlite hinge. Here is an ultra close-up of the hinge (it is the line to the right of the inter screw top).
Compare the smooth to screwhead the routed line to its right. The routed line is nigh on perfect. We have worked very hard to make sure our routing leaves no burrs. So good is the finish that the spine (to the left of the inter screw) barely shows at all, even under magnification.