You'd need Blender anyway to export it to a format Paint3D can read, and them probably need Blender again so you can put it back in the game. Blender is also a MUCH more powerful program and it's free so.... why?
Paint 3D is a joke, you can’t do any actual 3D work in it. Use actual programs like maya, 3dsmax, and blender. Contrary to popular belief you don’t need to use blender if you don’t want to