Summary

two of those will hold a photoframe of 7 mm thickness at an angle of 15% tilted. I made it because two frames I had had the tendency to fall over all the time. This way the frames are really stable.
Adjust it to hold thicker/heavier frames.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/hX0Nf1TOi4d