Here it is, my completed files for Destiny 2's Graviton Lance. I have modified these files from the in-game model, aquired from destinystlgenerator.com.
Modifications I have made were with the concept art for this gun in mind (image shown in the gallery), and as such some details may be slightly divergent from the exact look of the gun in-game.
The model has been resized to fit normal human-sized humans, since Guardians are apparently huge, and it measures in at 26in (66cm) long.
The pieces are designed to be assembled using 1/4in wooden dowel rods cut to appropiate lengths. Most of the model is designed to allow it to be dissassembled even after completion, and to be painted in separate pieces. The dissassembled picture in the gallery shows the pieces that don't require any glue to stay together after final assembly.
The magazine is designed to be held in place with 1/2in x 1/8in round magnets, and is fully removable. The tubes on the side are 1/8in clear air tubing, I have not included any file for these to be printed, but I may do so at a later date. I think the tubes look much cooler as actual flexible parts.
I have also included 2 files for a display stand that will hold the model up.
You may notice that the barrel shroud(?) does not have the slots that are there on the in-game model. It would appear that those details are not actually part of the model's geometry but rather, I would assume, part of the texture applied to the model. I could be totally wrong about that, but regardless, that detail is not part of this model since I am not experienced enough at 3d modeling to add it myself. It could easily be painted to add that detail, but I chose not to on my finished model pictured.