This article explains how to create a 3D drawing in Microsoft Paint 3D by drawing shapes, changing their attributes, and rotating them.
Microsoft Paint 3D Tutorial
Set up the canvas you are going to draw on. Choose Canvas at the top of the program to begin.
Enable a transparent canvas so that the background blends in with the surrounding colors. Do this with the Transparent canvas switch. This is optional, but it prevents a final product with a white background.
Change the size of the canvas. By default, the canvas is measured in percentage form and is set to 100% by 100%. Change those values to whatever you want, or select Percent to change the values to Pixels as shown above.