OK. I have finally got around to sorting this out. I know the original model was full of errors and having it a single file was not ideal, so I have cut it up and run it through all kinds of repairing software. It does look like there might be errors in some of the cuts, so make sure you check before you print.
I have cut it up to fit my Wanhao Duplicator I3 Plus, so it the pieces are a pretty good size. Once they are all together, the gun should be about the right size. I have not added the 2 trigger handles, they are basic foam covered bike handles, so they should be easy to find. You will need to carefully drill holes to mount them, but again, not that difficult. I also haven't included the various cables, adding real ones will look better.
Some of the pieces are a little "softer" in their detail, but they are fairly big parts and the detail can always be added back in after printing.
I recommend using 2 part epoxy for putting this together, sorry, there are no keys, so the epoxy will give you time to set the pieces in place.
I hope this makes the Smartgun much more printable, I am intending to print it in the not too distant future, so I will post photos as I go.