as always another scale 1:1 model I think 5% infill will work instead of doing it hollow , but feel free to print it hollow if your printer is able , mine still fail when printing hollow ones. I made if for 20cm x 20cm x 20 cm work area , the instruction to build it are pretty straight forward Ill add the full minigun as stl file for reference. I added 5 type of bolt to customize it , print as many as you want and glue them whenever you like the most.