That's just what Marc Schreibman did after taking a course in fabrication. After a "5-6 hour print", he had a new LCD viewfinder in his hands. It wasn't easy, however:
I took many measurements of the camera body and LCD screen, designed it in Rhino 3D, and printed it out on a 3D printer.
The initial design wasn't complete, though: Marc decided to glue on a Canon replacement eyepiece to the new viewfinder. However, he's going to print a one-piece viewfinder next time. There will be a next time, right?