So Christmas Eve, my husband pulled out our radial arm saw and made the inital cuts and we used Dads drill press to cut the holes. They glued and nailed it together and Christmas morning, it was complete. As a test, I tried it out on their cats, since we stayed at my parents place until Monday. Their cats were... not very interested. They're not food or treat motivated, and they're pretty wary of anything new. Pulling string through the box just meant that they'd go around and grab it from the other side. Those cats are just too smart.
However, when we got it home to my little piggies, the toy was a hit. They've figured out how to get toys and treats out of it and how to push it around so that everything is within reach of their little paws. But the best part is that playing with it gets them all charged up to romp around the house and play with each other. I'm really glad they like it, I just hope it will hold their interest for more than a week.