I made one for my wife's Challenger. Used aluminum stock. One piece of 3" x 1 1/2" x 1/4" for the pad that hits the floor. Two 1" x 1/4" x 8" uprights with holes drilled every 1". The uprights are welded 90 degrees to the pad so the pedal arm slides in between them. The bolts go thru the uprights above and below the pedal arm clamp it. The multiple holes allow adjustment up or down. Helped my R/T a bunch when I was racing it.
Doug