you know what i just did? i have an xpen in the bunny room and there’s about 8 inches on one side that i had gridded off to prevent them from going behind the pen. i found an awesome box at my job that is the exact dimensions of this empty space (about 8 inches wide, 18 inches high, and 3 feet long). i shoved it inside this space (fixed the nic grids to block off the top so they can’t jump over) and i FILLED it with a phone book, and newspapers, and binkybunny packing paper. it’s stuffed about halfway full. the bunnies immediately burrowed into it. they had a great time digging in it, shredding the papers, chewing the cardboard. it’s similar to the BinkyBunny “diggy box” but rather than having shredded paper, they have to shred their own… now they go inside and then push the papers towards the front so they are fully submerged in their box.
look around your house (or your work) and use your imagination to “think like a bunny”! it’s actually a lot of fun to try different things with them, and you can do this stuff for free, or relatively cheap.