Photo composite - see the white crud in the seam lines? That's spray-lat. This Blackbird is on display on the ground somewhere. I did a similar Photoshop job years ago with a photo I took of the Blackbird by the parade ground at Lackland.
It's alllllmost there. They've got the rig right, and the motorcycle throttle thrigger, but they're missing some of the bulky structure (meant to disguise the MG-42) along the barrel, and they haven't hidden the MG-42's grip (which it appears was removed from the movie props altogether). And of course the drum that held the belt so it wasn't hanging down and visible.
Still, that looks fun as hell. The same guys built a funcitonal Pulse Rifle and have videos in that same range bay shooting it.
Interesting history on the Beech Starship. One of the first commercial aircraft to be made of mostly composites. I think only 5 are still in flyable condition. 2 live in Texas at Addison