Scale it by 0,001 and just mirror it for the other side.

It easily snaps on and off, but only when intended. I designed it to fit as tight as possible and so that a little nib slides inside one of the screw holes. It works quite well and feels more like a standard controller.

My wrists used to hurt after playing the deck for only a few minutes. I looked online for some kind of bigger grip but could not find any. So I started prototyping with paper and adhesive tape to make the Deck more comfortable for big hands. Pleased with how it felt, I modeled it in blender and used Valve's offical CAD files to make it fit. A few prints, changes and improvements later, it worked. Even better than I tought it would. Feels awesome for my hands and not loose at all.

The only downside for me right now is, that the deck does not fit in the case it came in with both extensions on. But since they just slide on and off, I just do that when I want to take it outside.