I don't think it really counts as a mod but I flipped around my flats for my Grados so that the slits give some space between the drivers and my ears, then glued on a softer fabric to cover the flats. Its still reversible, so I usually have them as flats for the first hour, inverted after that when my ears hurt. But, you lose just a little bit of the Grado edge inverted. Mainly belongs in this thread because of how ghetto the gluing job is.
When school gets out, im goin on a homemade C-pad project, which with undoubtably belong in this thread, as it involves PVC and wood, neither of which ive had any experience dealing with