I don't think it's built off a real gun at all. The mag bottom looks similar but if you look at the line of the slide it isn't straight, and the thumb guard is way to big to be any gun, then the trigger guard does not match up with where that blow back spring thing cove should be and then there is the distance between the bottom of the slide and where the blow back spring housing should be.
I think it would just be less work for any one to make this from scratch. It could probably be done in one day. It's not that complex, unless it has to fire it just wouldn't make any sense to build it off an existing item.