I agree that hardware cloth is not the way to go. I have an old wood hutch with hardware cloth bottoms, but the rabbits also have wood 'shelves' to hop up and rest on. They spend most of their time up on the shelf/ rest. Also, the "Nursing Doe" poo won't fall through the hardware cloth holes. Does eat and drink a LOT when nursing and have large, soft stool pellets that I found will hang up on the small hardware cloth holes.
All of my self-made cages have the 1/2" x 1" x 16g floor wire. I still like to provide a resting spot for the buns, whether it is a piece of cardboard, a piece of wood, a carpet square, etc. just so they can get off the wire to rest. Of course these items inevitably get pottied on and either need to be replaced or washed from time to time. I like the cardboard because it just gets thrown in the compost, but some buns shred it and can make a bit of a mess in the cage doing so.