Airsoft Canada - Shotgun "holster"?

hey guys, I've been poking around and I'm looking for a holster for a gun I'm custom building.

here's the issue though... it's a double barrel sawed off shotgun ;) .. I've been sorta looking at the adjustable uni holsters for large frame pistols... but I dunno

my only real requirements are:

Molle attachment
one hand draw of some form.

I haven't decided if this will be on my side, back shoulder or a drop leg so I gotta be able to get it out of the holster and in action with one hand quickly ;)

oh and it doesn't have to be gucci ... I really don't care about the tag on it so long as it works

thanks for any help :D