I am going to mod 2 Dyson Hoover handle arm thingies (the things on the end of the tub to hoover corners on the cieling and junk) being I have an old one and new one from burn out hoovers we have and the thought amuses me.
My question for you lot is the internals of which gun would be best suited to each handle.
I was thinking something like a Nitefire would be simplest, but the opinion of those here would be appreciated.

the top one has a 1 inch metal tube to stick things in.
the bottom one has a 30mm tube.
my intention is to cut a hole to load darts in from the side of the tube(s).
Again this isnt meant to be an amazing gun it's meant to be a "This amuses me" project.
and on a thought looking at my wall, it probably wouldnt be too hard to integrate a buzzbee rapid fire rifle into the top one.