When I got my Ti-Scout I was rather happy with it and overall like it- but I found that when I had it in my pocket it wouldn't stay closed and would sometimes open enough for the sharp edge of the bottle opener to catch on the fabric in my pocket, and I also worried about it scratching other things I might have in my pocket. When I got a roll of TPU Air and did a test print of it, the first thing that came to mind to make from it was a 'cap' for the Ti-Scout, so I took some quick measurement and threw this together in OpenSCAD. 

It's quite basic, but gets the job done. It pretty much has to be printed with TPU Air, but regular soft TPU might work (I'd probably scale it up a few percent though since it will likely stretch less than the Air does). Printed with TPU Air at 270C to get it to foam as much as possible it is just right. If you have the settings right it does just fine despite the slight overhangs.

Hope you enjoy it!