My previous rabbit pen was something of a flop. It was made of fencing that had rabbits on the name and in pictures on the package. In a week we lost one rabbit, had one jump out and get caught, and had the rabbits look awfully comfy with jumping "rabbit fence" height stuff. A nice big rabbit pen doesn't do much good when you can't leave the rabbits in it.
Anywhatzit, I took the pen down, cut the wide-spaced parts out, and made a smaller 6'x6' pen with an open side for the cage to sit beside and smaller spacing on the sides. I also put a top on it with paneling and some saplings so they can't get out.
Anyway, unless they start digging out they should be pretty well contained.
(UPDATE)
They tried to dig out. Their escape attempt seemed to be aimed more toward China than outside the pen. The cotton-tailed miners didn't seem fazed by my explaining that digging straight down would only lead to molten rock and eventually the southern part of the Indian Ocean, so I was forced to pull out a piece of chain link fence for a bottom to the pen. They can still sniff and eat the grass through it and can relax on hay I put in there as well. Waskawy wabbits.
