If the board is bumped, the balls roll on the floor, the table everywhere so fast it’s hard to find them all. I have added a stick magnet to my box. And made a mat of Easy liner shelf liner. It’s a foamy, shelf liner, that does slow down the rolling balls. It catches many of them.
Tatwie-- I like your magnet idea. Others have suggested placing the board and its stand inside the box top, which has worked for me and the 7 - 10 years old kids that use it. When the balls fall out of the board they fall into the box top rather than the floor. BTW if you cut a strip of plastic about 4" by 1/4" and place it above the chutes for the triggers, it acts as an interrupt so that you can drop only one ball. --DonV