When drawing 3-dimensional objects, you have to pay attention to the length, width, and height or depth of the object you are interested in drawing.

I like to use an xyz-coordinate system and draw in the length and width of the object first and then draw in the height or depth.

Draw a rectangular solid that is 2 meters in length, 2 meters in width, and 2 meters in depth.

y +

x +

z +

y +

x +

z +

y +

x +

z +

When completing the shape, notice that you are drawing a face of the object on a plane that is parallel to the xy-plane.

This procedure should be helpful when drawing most simple solids.