This is the Split Pin to use in hinges and pivots. 

Using OpenSCAD (if you have not used, it so easy, download it and use it) you can configure the diameter and the length of your Split Pin, and print in PETG. 

There is also an STL. (length 7mm diameter 5mm) and 3MF (length 7mm and 10mm diameter 5mm) file with pins already in if you don't want to play with OpenSCAD. 

All you then do, is create loops on your parts for the joining of the hinges together at half the length of the pin (The flange and the barb are addiitonal on each end, you could recess them if you want a neater finish obviously). 

And when printed clean the pins, push them into place.  Should be a snug fit, you may want to play with tolerances - i'm going to make my loops 95% of the half the length of the pin, just for a sure fit, i don't need the hinge to be tight or gritty. 

The other project you see in the image will be coming later - it's an Insulin Vial Holder for use with Omnipod 5 - where the lid acts as a support for the syringe whilst dispensing the amount required.  I had to solve the split pin topic first - next to refine the case which is currently in proto-type.