Is there someone able to create a mod like this? I wanted to introduce this weapon in the game, but I can't create textures and animations.

But first of all if you don't know what is a sling search slinging.org
I would suggest a sling which is 60 cm long about, and the same technique for both sneaking and normal: a sidearm style with a 45° inclination.
There are a lot of things to develop, but I hope that from this idea can grow something good and innovative

Thank you all and... I'm sorry for my bad english xD