DeSantis made this rig for the UZI and MAC series back in the day. Pretty large and heavy guns to be carrying.
Similar items are/were available for the MP5 K and PDW
Of course the Glock 18 can fit any CCW rig made for Glock.
here are some UZI SMG holster designs from history.
http://files.uzitalk.com/reference/pages/cases.htm