if you want a ghetto design, i dont use this to catch brass, but it might work for that depending on the rifle.
i bent a long window screen at a 90 degree angle, and weight it down to the table. i wasnt trying to catch brass, but i did end up catching quite a bit of it since the screen slacks. i only use it to block the brass though, because my rifle throws the casings 3-4 benches down and it kicks it pretty high. at the very least, its a really cheap way to at least make sure your neighbors dont complain, and if your rifle or pistol isnt kicking out shells too hard, it will probably catch most of the brass too.