After mucking about with gmod addons, I stumbled upon (or re-stumbled) the laser nonce.
The laser nonce was used for laser dance.
Essentially, it was a slow-firing rifle (Or revolver in later versions) that would fire a single laser beam (I can't remember if it instakills or takes a few hits), and knocks you backwards a stuff TON.
Essentially, i'm asking for this to be made. Hell, pinch the lego blaster model and script it to function like this
It should come in 5 or 6 variants:
Red, Blue, Green, Yellow, Grey, and Rainbow (shoots a random colour laser each shot, if possible)
