So I wanted a small, and thin friction hing for another project, and I couldn't find the metal ones that they use for the iPad's Magic Keyboard case. So I design my own the parts I had on my desk.
The smallest nut that I had was 4mm wide which really limited how thick the design can be. The result is this
It folds flat at measure at a maximum thickness of about 10mm
It works a lot better than I thought it would, especially since this is my first prototype print. Need to figure out some things, like to stiffen the arms and to prevent/reduce twisting.
But as a basis to start from this works nicely. I think if I add a TPU washer on the back end, I might be able to get it stiffer and more consistent feeling. But I'll do that at another time.
You might be able to make it much stiffer by adding more of the arms parallel. The force should be consistent when you tighten multiple of them with one screw.
I could achieve the same effect by making the arms thicker. Though I am thinking of printing the screw caps in TPU to see if I can make it stiffer that way.
Trying to keep the parts the same as the main thing this belongs too. M2 threaded inserts and 5mm screws. So not a lot of flexibility when it comes to thickness. That said, as a MK2 I'd probably make it 2mm thick rather than 1.2mm since that's my goto size for stiffness.
What about a dab of hot glue as a kind of medium between the head of a bolt/screw and the plastic it’s in?
This way you get some of the “grip” from a malleable material that’s also pretty easy to get ahold of for most people.