This is a pretty darn close screen replica of the Blastech SE-14R Blaster used by the Death Troopers in Rogue One. The same blaster is also carried by a lot of the Storm Troopers in the other Star Wars movies though Rogue One photos were used for the reference for this version. The blaster was originally created by using a kind of obscure gun called a Rexum Favor which was a sub-machine gun used during WW2. The barrel and stock were cut off of the gun and a cheap Tasco scope was mounted backwards on the top. (These scopes are available in a lot of discount stores and cost about $17 so there isn't any point in 3D printing one.) This blaster was also used in the original Alien movie. Is speculated that the special effects guys for Alien might have even used one of the blasters left over from Star Wars.

There is a free version of my design that I posted on a few sites. This is an upgraded version and has been printed numerous times. I will not be upgrading the free version and I have this model priced very reasonable to make it worth getting the upgrades and knowledge that it has been printed many times with a lot of success.