how could i make 3D art ?

i was just thinking of this when watchin gthat harry potter tiny docu how they made some parts 3D.

then started up photoshop and thinking how could would be to have a 3D background theme for windows or my ps3.

that is watchable when putting 3D glasses on as well having the tv for it ofcourse.

but would it work? would it just work as 1 non moving screen?

i mean aint that the most awesome. to create your own 3D?