I used a cardboard box as catch box in house for weeks (the one shown in first picture). My lovely wife asked me yesterday said: why don't you make a better target? So I spent about 2 hours to finish this new one today, could not called it "catch box" but it works. The basic idea was coming from one youtube video I forgot the link because I saw it few months ago. The material was cut from plywood because I have one measured 240x120cm and I cut it into 60x30cm pieces already. The new "target" is 45cm width, 60cm height. A heavy black towel is used as blocking background, a cloth foot-pad to catch falling steel balls. Both are "clip on" so it's very easy to replace if necessary. The new target is "foldable", so it's good to use in house because I can "fold it" and put it away without take off the towel and foot-pad. Here have three pictures I took, by the way, happy new year!