Keep your bunny cool in hot temps. Rabbits get heat stroke easily, this gives tons of great ideas on how to prevent that. - I used the frozen soda bottles when raising rabbits in California they worked great!
Terra Cotta Lid with Ice bag underneath: Get lids big enough for bunnies to lay most of their body on. lay a smaller flat dish on the ground and fill a bag with ice and put it in the dish and flip the plant lid over on top of it to make an "ice bed".