one quick change you can make is make the wall flexible - so maybe thin gauge metal only fastened on two points - for a rubber-band effect, replicates to some extent what pneumatics do.
Somthing like:
http://www.youtube.com/watch?v=aszDpJW_8bA
but with only two hold-downs - the tension follows the Frisbee.
also you can try cutting up the latex and riveting it on - maybe that helps because it will reduce movement of the latex.
cheers
arun