Geezer here: Okay, here's some of the straight skinny on Dural prods. I started making lite crossbows (50-75 lb at 7-8 inches of power stroke) Starting with Jayhawk aluminum alloy prods that were approx 28 inches long, 1.75 inches wide at center and @ 3/4 inch wide at the ends. 190 thousandths thickness (approx 3/16 in.) made prods capable up to about 75 lb with lock 11 inches from belly of the prod. I once got some 'experimental' prods from Jayhawk that were 1/4 in. thickness. The additional 1/16 in. thickness Doubled the power. Yes, spring rate usually varies by the cube of the thickness, but only direcltly with the width. So double the width and get double the power (less losses for air resistance and extra weight) but add only slightly to the thickness and the power goes up exponentially (but a thicker prod is actually being stressed more, so the limits for draw length should be reduced a bit) Anyhow Jayhawk told me they were using 70-75 T6 aluminum alloy. That's what I used when Jayhawk (Oklahoma) sold the business. For @ 10 years I made my own aluminum prods, while Alchem and later Slobows started making steel prods based on the old Jayhawk asymmetric shaped prods (Jayhawk's prods were 28.8 inches cut as blanks because that minimized the losses from a 12 by 4 foot sheet... cut into 10, 24 X 28.8 inch sections for easy handling when cutting. That's why everybody builds 28 inch prods.
Anyway about 15 years ago, Darkwood Armory took over making my aluminum prods. Now I buy exclusively from them in aluminum as well as some steel prods @ 150 lb. But I still buy most of my steel prods from Slobows, because they offer a variety of prods in various weights.
For you guys out there with old WhamO Powermasters, it is possible to refit those with 31 inch steel prods. Alchem and Slobows used to offer those, and no doubt my friends at Darkwood would do much the same for a reasonable price.
If you're determined to make your own alloy prods, it can be done on a standard bandsaw, with metal cutting blade. Just go slow and lubricate a lot. Then file/sand the cut edges smooth... particulary the nocked ends. It doesn't hurt to stress relive (bevel) the edges as well. You can use the cut prod flat, but I actually have a simple wooden cam bender to put a bit of recurve in the ends... bending the ends won't hurt the temper, but you can only do it once. If you straighten, rebend, straighten, rebend, eventually the alloy will work harden and break.
Afraid of breaking an alloy prod? It does happen after long periods of use/abuse. Just wrap the prod with thin (goatskin is good) rawhide: dye or paint it pretty. Now you're in no danger.