Below is a mockup to see how the hinge fit in the current project. To the right is the smallest hinge I had in my stock and I didn't like it. The hinge is too large.
So I had to make my own. First I draw the hinge parts in the right dimensions and then cut the parts from a piece of 0.1mm brass-sheet using my cnc. That was an expensive experience because I broke a milling-cutter in the first try. But I made a hinge in the right size.
The hinges was then made using the photo etch technique. Here comes the nightmare :-)
The first sheet I etched from the same 0.1mm brass sheet had parts for 96 hinges but after etching and trying to assemble the first hinge I discovered that the brass was too thin. When opening and closing the hinge it just fall apart. Then I tried etching 0.2mm brass using the same layout.
Doubling the thichness to etch also doubles the etching time and that gives problems with socalled underetching and I haven't thougt about that. So back to the drawing board and after a few more trial and errors I managed to make this sheet of hinge parts.
5 hinges before next step
Why not glue? Because glue is hard to control in small spaces and can easily make the hinge unusable.
For soldering I use solderpaste normally used for soldering small electronics. The solderpaste contains flux and pewter and can be applied very acurately in small amounts. I got mine from ebay and despite the small container says something about a shelf life of 6 months and cool storage it works well after about two years in a drawer.
Here is some solderpaste on a bottlecap (diameter 28mm) Half of the paste that the red arrow points to is placed on the hinge.
The hinge is placed on a heat resistent surface.