The plastic hinges on my FiiO µBTR bluetooth receiver broke, so I made a replacement.
You still need the original spring and the small metal bolt.
If you lost the bolt you might source a 1mm bolt from something else but I don't think you'll have much luck if you lost the spring as well.
Print time is around 21m with my MK3s with a 0.1mm layer height. You should stick to 0.1mm or lower, 0.2mm could work but I didn't try since I wanted to get the hinges as smooth as possible.
Here is the Fusion360 link so you can make edits if you want to modify it: https://a360.co/3Kxdi37
The author marked this model as their own original creation.