Having the imagination I have I instantly put in on my shoulder like a rocket launcher and it got me thinking...
If you take one of these (I have the wrapped paper tube not this nifty hard plastic one)

and then put this in it

Attach a teether to the end so you can pull the sling back.
And finally paint it like this.

We all know typical shell launchers are cool but expensive and in the long run don't perform like we'd like them too.
Using tennis balls or racketballs as a projectile to use a rocket launcher or mortar like it should be on the field.
Also, by attaching a swivel and baseplate with a pully could allow you to make a mortar out of it.
Thoughts and ideas on it? And would this even be allowed at a game?
Could be an interesting game changer!
Anyways thats what I spend the last ten minutes thinking about.