Jim, such brass catchers have been around, both commercially and homemade for quite a few years. The problem with using one for a shotgun is that it would have to be attached to the gun itself (the handgun catchers come in models attaching to the gun or to the wrist of the shooter).
So, unless there was a real fast way to get the hull out of the "bag" and into a pouch and reload before it was your turn to shoot you would either have four other annoyed squad mates or you would have up to 24 hulls swinging below your gun as you tried to shoot the targets.
Shellcatchers, from rubber bands to plastic or plastic and metal are about the only choice if you want to keep your hulls from hitting the ground.
Tron, for example, installs a little "knob" (he may call it something different) that he regulates to drop your hulls in one spot, but they still hit the ground and lots of clubs, mine included, will not allow you to pick them up.