I believe you will find that for end plates that thin stuff will kill performance. Your reactor will have very hot spots near the electrical connections and almost no production at the opposite side. I have quite a bit of experience with Nickel. It is very very soft. Even the thick stuff I was working with wanted to warp when media blasted. I don't believe you could blast foil at all. The blasting grit would quickly erode through it. It is my opinion that even a slight amount of unbalanced pressure in the reactor would warp the neutral plates so some were closer together than others and the losses in the end plates would make the reactor far less efficient than a stainless device. If you found a way to bond the Nickel Foil to copper plates with a good electrolitic glue than you may have something but the copper could never touch the electrolyte and the cost would go through the roof.
Larry
2008 Nissan Frontier 4X4 Nismo. 12 MPG baseline with my normal commute and heavy stop and go daily driving. Generator installed and working on 3/29/2009
Up to 14.5 MPG with no enhancers. Still testing the effects of lots of HHO and no electronic enhancers.