This is a deep easy to handle 55mm lens cap. It is 4 pieces 

1. outer shell, 
2. buttons with spring, and 
3. 2x jaws for each side

The lens cap snaps together after printing.

Please use PLA and 0.20mm quality settings. See notes for PETG below.

To snap together squeeze the button and place them into the shell. Bend the shell slightly so one side of the first button snaps in. The repeat with the other 3. 

Add the jaws assembling them as lego. They will require some pressure with PLA print to get into place but then seem to stay secure.

If you print with PETG the holes where the jaws snap may need to a bit wider e.g. 0.15mm to 0.2mm bigger diameter or so. I found PETG to require holes bigger then the inserts. With PLA it seems that there is not such need.

[6th of July 2022] I uploaded updated model that improves the grip to the lens and eliminates wobble. I am pretty happy with the latest version.

[28th of January 2023] I added real M55x0.75 threads to the jaws and corrected some dimensions to further improve hold. Cap sits much firmed now. as the jaws fit perfectly with the filter thread.