I bought a used M3 for my return to film photography around the same time that I refreshed my eyeglasses. My prescription runs about $900 for new frames with all the bells and whistles: progressive high index lenses to handle the high correction for my prescription, anti-glare and scratch protection coatings, and transition sun glasses.
One problem. The M3 viewfinder ring is metal with a serrated outer edge. The first time I put my eye up to the viewfinder and heard my lens contact the viewfinder I realized scratching my glasses was inevitable. I knew just the sound of my lens contacting the viewfinder was going to be a distraction.
The only option I could find was a plastic snap-on Eyeglass Guard for the viewfinder from DAG Camera Parts. ButI still had the distracting sound of my glasses contacting the viewfinder. I wanted something that was quiet (no distraction) and compressed against my glasses when I buried my eye in the viewfinder.
Here’s my temporary solution using a 1-1/2″ x 1/16″ roll of self-adhesive neoprene and a couple of circle punches from EK Tools (1/2″ and 3/4″). This is only a temporary solution since it is easy to dislodge the neoprene/adhesive.
I have since found a better solution in a future post.