I gave up on using nutplates, owing to the difficulty in dimypling the steel channel. Instead, I made the holes slightly large, and used the tried and true farmers method of welding a nut to the back of the metal. I fabricated two outside panels, through which the cat's whiskers pass and onto which the nylon block attaches via sheet metal screws, and alodined, primed and painted them with some other miscellaneous parts. I also sandblasted the vertical fin channels after all the welding, primed and painted them. BTW, putting the paint and catalyst in the refrigerator really helps avoid orange peel in these 90+ deg days.
