I found this model on Printables; it’s really useful, so I wanted to bring it to MakerWorld for other users to use. If you like this model, please rate it and/or give it a boost.

From the original designer:

Some iMacs (from 2012 onward) have a problem where the plastic spring clips at the point where the display stand connects to the inside of the display case break. This causes the tension that keeps the screen at the proper angle to be lost. Some repair methods require removing the screen (a risky task) and replacing the plastic clips with metal ones. As an alternative, this stand fits tightly against the edge of the stand to prevent the screen from tilting forward. It can be adjusted along the edge to change the screen’s angle.

https://www.printables.com/model/269854-imac-display-wedge