I made myself a free standing catcher out of 1" pvc and nylon window screen. It's 6' tall 3' wide, with a 3'X3' opening. By only glueing parts of it, it takes down into a roll 3' long by about 5" in dia. Setup is about 2 min.
Think of a 6' X 3' rectangle with a crossbar in the middle. The screen goes around the top forms a pocket then goes around the crossbar. By sewing the sides of the pocket shut it forms a collector that hangs 18" down from the center crossbar. The crossbar is offset 6" to the rear to create an angle on the screen to deflect the brass down into the pocket. I used 2-10' pcs pvc pipe, 4-"T" fittings, 4-elbows and 4-caps to close off the "feet". The top and middle have crossbars the bottom got 2 of the T's and 8" pieces of pipe to form the feet. If it's windy just put a sandbag on the feet.