Ah, that's much clearer ... we were thinking that you wanted this to bend as your knee bent. To use it to hold you knee pads on, you would want spring steel in the "holding" shape. Then it would _flex_ enough to remove it, without needing to bend it to a different shape.
As a wild-ass guess, I would say the piece should be about 3/4 to 1" wide & maybe .030 thick. That would give a pretty strong hold & you need that.
Bob