This is my "hello world" program for SCAD. There are already multiple reading glass cases on line but I wanted a single piece that protects the glasses taking up the smallest possible space.

The included STL file prints a case that will hold a set of glasses 130mm temple to temple and 40mm top to bottom of the frame. If your glasses are larger or smaller, open the SCAD file with OpenSCAD, adjust the glassesWidth and glassesHeight values and press F6 to render your custom case. File->Export the rendering as an STL file and print.

PLA is plenty sturdy with a 2mm wall. If you like, play around with the caseThickness in the SCAD file and the fill density in your favorite slicer.

PLA is much softer than any plastic lens material, no need for lens protection sliding the glasses in and out of the case.