As stated in the title, I saw the video by TFBTV about their shoulder fired, battery powered, 22LR Gatling Gun and I think this would be one of the coolest projects ever if anyone would tackle this for the 3D2A community, even if it was locked behind the SOT licensing.
That certainly puts up a challenge, as I stated above it would be cool if someone made one or the other, FRT is obviously better for the general 2A hobbyist, but even if someone made an SOT version and released the files with warnings of “for SOT’s only.” Perhaps for the FRT version you have a “grip safety” type button that runs the rotating barrels at a fixed speed, and a trigger linked to the bolts so as the bolts move back and forth chambering cartridges it forces the trigger forward and backwards.