Not a great design for compactness. Still working on the wiring and alignment. I'm hoping everything can fit with the back lid on. Only challenges here, no promises.

Update since first post. The cable connector mount has been repositioned to the best possible angle. All posts have been changed to hole mounts. I used m2 screws. A bit of heat to open the holes would be helpful. I heated up a thick needle to expand the hole and get it started, then I used a lighter.
Also, before assembly, use heat on the area indicated by the arrow. Give the area an ever so slight bend up to make clearance for the ribbon's chips. Maybe a mm or two rise.

I included the standoff mounts for the three boards if needed.

I broke off the connector tabs so I just added a screw hole instead of reprinting. The ribbon mount has been updated in the .stl file. I moved it closer to the screen cable for a better angle. I have not printed this version. I will just cut it off and use ribbon converter female.stl.

m2 and m3 screws used.

https://www.waveshare.com/product/displays/e-paper/epaper-1/7.8inch-hdmi-e-paper.htm?___SID=U