jmc900:
Check the Digi-Key catolog or web site. They carry Injectoral products, with small quantities of 1/2, 1, 2 and 4 ounce copper. I have seen thicker weights, but are usually special order, and with minimum quantities. You could plate additional copper on the surface to any practical thickness. For those who want to know, the ounce is the weight of one square foot of copper for the copper thickness applied. One ounce copper is about 1.5 mils thick. Unless you need narrow traces, etch undercutting should not be a problem.
elecmec