If I were to contemplate doing something like this I would begin by determining the diameter of the rings that you are wanting to use. I would then figure circumfrance of the ring by muliplying diameter by Pi. (3.1416). The next thing to consider in your layout would be the distance between the upper an lower rings. One would need to allow for overlap at the top and bottom of the shade so that the paper would be fastened to the ring by folding back on itself and gluing. Additionally one will need to allow for an overlap in the circumfrance of the two rings, again for the purposes of gluing. I would then lay this out on a flat sheet of paper, cut it out, and glue it up. There may be other ways to do this, but this is the way that I would proceed. Good luck and have fun.