I have a scrap-ma-bob that I love, but I also use a gift bag that stands upright on the table ... then I just empty it out and refill ... easy enough yo fold up and bring to a crop
Great idea using a kleenex box. That would be so nice to take to a crop.
At home I have a small lunch size brown paper bag taped to my table. I fold down the top about 2 inches to make a sturdy rim. It works good for those small blue tabs off the photo splits.