A digging box - tote filled with sand or dirt (black earth / potting soil?) and covered with a lid - make an "escape hole" in the top and bunnies can dig away without making a huge mess! My bun would love this!
Example: a rabbit could have 1 egg cup of pellets and a pile of hay per day, plus a selection of vegetables. One day it might be a cauliflower leaf and fresh basil/parsley and another day blackberry leaves, fresh grass and a small carrot.