This is a 28mm model of the British 6 pounder anti tank gun - also used by the Americans as the 57mm ATG.
It is a remix of sheptr's 3d model.
I cut the actual gun and gun shield from the carriage, added an elevation wheel on the gunner's side, and did some creative licence to create recesses to allow easy assembly of the printed parts. field guns and the like are actually a lot tougher to make 3d copes of, as there are so many angles and unsupported bits.
I also created an axle and made recess holes in the rear side of the wheels.
You MUST use supports to print this. I used supports and a 4 mm brim just to be sure. I tend to be a bit Type A.
Be very careful removing the supporting material. you don't want to harm the axle or other small bits. look at the .stl for each piece before cutting away.
I made two barrel options - one with the original straight barrel and the second with the longer barrel with muzzle brake deployed later in the war to deal with the newer ammunition.