I have thought about this and thought about it somemore...I posted an idea of machining a sleeve like you are talking about on the net and a guy gave me an awesome suggestion.
At crafts stores, they sell a product that is pliable like clay at first, you shape it the way you want and bake it...it hardens to the consistancy of a hard rubber ....it also comes in colors, I just wanted black. I cant remember the name of it and I happen to find some Pre bans for my Compact...so I never pursued it any further. Check into it, it sounded really easy and perfect for what you are looking for. Shoot well