BINGO!
Use 'region' is the exact solution I were looking for. I went digging in my AutoCAD reference book and found 'region', the command that can turn any 2D shapes into solid surfaces. Thanks goes to cadshite for the help out!
To pardal: '3D Face' is a command that turns the asigned area into a solid surface in the rendered view, but it is only good for triangular or rectangular area. If you try to render any 2D shapes, you will see nothing but hollow frames standing in mid-air. The point of making a 3D face is so that you won't be able to see the object behind.
To IFRs: The reason I don't use 'extrude' is because I don't want any thickness at all. Like a circle cut out of a very piece of paper--no thickness but it is still nonetheless a solid.