A friend at work was talking about spinning prisms, that will be a second choice since it appeared a more sofisticated and dificult aproach.

I'm waiting to finish my engineering course and play with these kind of things in my free time... Steve notted that with steppers I won't get much due it's response... I think it worth a try... just for simple shapes... hearts, squares, tringles, circles... I think it may work... besides, it's more fun trying to do the impossible :-)