Garry is correct, Royce, that approach would be really expensive. I do start with some of the top sections of the rails on my clear valve covers cut from inside the outline of the bottom rail, so that helps, but even so it doesn't make sense. I start with a 6" X 28" piece of stock for each valve cover. I can get five of those out of a stock 1/4" thick X 144" long piece of stainless. My local metals distributor charges $360 for the 144" 304 stainless piece, so that means each pair of valve covers could cost $144 just in the metals material. Never mind the laser cutting cost, drilling, tapping, and chamfering cost, etc. Oh, and let's not forget about the cost of the Lexan, plus vacuum forming it and cutting the holes in it, and then assembling the whole works, which is not a trivial task.
I looked at all this when I started making these things years ago, and the way I'm doing it is the most cost effective. The billet aluminum, which has to be thicker, is still a lot less expensive than the stainless. Even so, I was practically giving the clear valve covers away at $300 per pair for the plain ones, and around $375 per pair for the ones with the breathers installed. With all the price increases in the 6061 billet aluminum that I use now, I'll probably have to go to $450 - $500 per pair if I ever do it again. The guys who got on board early were the ones who were the winners on this deal.