Another note for DP: Get a bunch of small, 2" spring clamps. They are perfect for creating doors and roofs you can open and "lock", as well as attaching litter box and food dishes to the cage so bunny can't tip them over. We got ours at Home Depot for like 60 cents apiece in the tools section. Ours are green but I found a pic of a similar clamp online:
While at Camp Swank, we found ourselves wishing we had brought the useful clamps for all kinds of things. Next year, a handful go into our camping gear.