Since i totally suck at Lua, i would like to suggest a SWEP!
The Rope Gun!
Description: A Crossbow that shoots a small prop like a can or something. when the prop hits something, it creates a rope at the hit position that is constrainted to the prop itself. then it bounces off the hit position and hits anothe position where its going to delete itself, constraints the rope end to the hit position and adds an extra rope lenght that is around -30. thats it.
i hope someone can do that for me!