I used 304L Stainless Steel 1" x 1/8" as a "Flex fender" on my Son's and for a couple of the kids at the local.
It has enough stiffness to act as a fender but not enough flexibility to actually work as a Brake- so it just keeps you from hitting the wheel.
Depending on your weight it will depress down far enough to hit the wheel but it does have enough "Spring" quality (compared to Mild Steel) to not stay bent down.
I don't have a photo to post up right now.
TSI deck on the left- you can sort see the shape- a very squared off S- just bent it in a vise with a hammer.
I have some extra stock of SS if you want me to send you a piece