In 1943 the Soviets took about 200 captured German Stug IIIs and rearmed them with Russian 76.2mm guns. They cut off the top of the Stug III chassis and built a new armored box to mount their gun in. 20 of the vehicles were converted as command vehicles with with a German tank cupola mounted on top of an extension on the right side of the armored box.
I started with Bergmans excellent SU-76i in his 1-100 WWII collection (https://www.thingiverse.com/thing:3553160). I reduced the diameter of the gun barrel since I am using a resin printer and added the command bump out and armored cupola in TinkerCad. One file is closed hatch and one is open. They are both 1-100 scale. Enjoy