Hack to Make RF Rear Lens Cap work by feel (like an an EF cap)

Below is a hack I tried to may an RF cap work more like an EF cap, so you don't have to visually line up the mark on the cap with the mark on the rear of the lens. You can take the cap on and off by feel without looking at the lens or the cap.

I started by making a 3-D model of the old cap and then seeing if there was a way to cut the tabs down where there would still be 3 tabs left while at the same time fitting onto the bottom of the lens.

There was a solution, and I 3-D printed a custom cap that worked. But then figured it would be cleaner (not wanting to cause any junk onto the back of the lens that might make it to the camera's sensor) and easier to cut down the tabs on either a Canon or a 3rd party rear lens cap.

I 3-D printed a plastic template (I have posted a paper printable version at the end). I just the template, and I score where to cut with a sharp knife. You also have to cut down the one "stop" that prevents you from overrotating when removing the cap (more on that in a bit).

The 3 images below show the process of modifying a (3-D party) rear lens cap.

I used some diagonal flush cutters and a hobby knife to cut off the ears and the stop tab. There is not a lot that needs cutting.

Cutting off the "stop tab" (which prevents over-rotation when removing the cap) while supporting the 3-Way universal orientation will allow you to over-rotate and relock the cap when removing, but this will only happen if you are not simultaneously putting a little outward force to remove the cap.

If you try this, I would highly recommend cleaning the cap well after all the cutting to eliminate any loose particles.

The resultant modified RF cap will work on either RF or EF lenses. The same template can make an EF cap work on an RF lens, but note the RF cap will protect the seal rubber on "L" lenses where the EF cap does not.

Below is a hopefully-to-scale template (if the posting process does not strip the scaling).

Paper Printable Template

This may have been done before because it seems obvious, but I have not seen it.