The Leica 50mm Summilux is an amazing lens, probably one of the greatest and most compact feats of optical engineering ever produced. But for those of us who hold nothing sacred and have access to a 3D printer, there are always improvements to be made.  These printed "shields" improve the ergonomics of the focus and aperture adjustment rings.   
***They:***   
 -  Increase accessibility by enlarging the body of the lens to become a flush continuation of the Sony E-Mount    - Add tactile indications of where each ring is in its rotation   - Provide a distinct texture for each individual ring.  
***They also:***  
 - Add a decent amount of physical protection to the lens,   - Obscure the fact that you have an expensive lens on your camera   - Look kind of cool.  

(*These rings slide over the lens without any modification to the lens. They mesh with the textures on the lens so that they don't spin freely. My Summilux is a V2 - these should also work on a V1.  They are held on by a screw-in hood. I used a 43mm to 55mm step-up-ring and an appropriate hood and filter, because that's what I had.*)