I created an OpenSCAD library with some basic reusable modules for display-frames. Two of my example frames are for the Inky-Impression 7.3 (Spectra6) and Inky-Impression 4 (ACeP):
These examples are table-top stands, but I also have a module for a more classical frame:
You can find the modules in my repository. Note that this is a “no screw - no glue” design, so you probably have to tweak some tolerances. That is also the reason that I don’t provide ready to use STL files. Chances are too high that they just don’t fit.