The Earth Federation Cargo Plane in 1/400 scale is a heavy aircraft that can carry several tons of supplies. There are a pair of anti-aircraft guns, and the cargo box can be assembled closed or opened.
While you are free to rescale as you see fit, I've also included presupported files at the aforementioned scale. Happy printing!
Notes:
At 1/400 scale, each part fits comfortably on my Voxelab Proxima 6.0, and scaled up to 1/144 all the parts fit in an Ender 3 build volume, so happy printing!