Hi! We like lots of details here so:
I assume you are speaking of a metal wire kennel.
Do you know the size of the kennel?
What breed of bunny do you have or what is the size of your bunny?
How much time will the bun be spending in the cage?
I have a metal wire dog kennel that is used as my buns cage. He is only in it at night while we are in bed or when no one is home for short periods. He is usually out for approximately twelve hours a day. I have a Flemish giant so he has a large cat litter pan at the back of the kennel. I have a feeder hanging above it for his pellets. The feeder was good for when he was younger because I could fill it with pellets for a few two day trips we took and I knew he would not run out. Now that his pellets are limited and it is harder for him to eat the pellets I will be purchasing a dish that can attach to the side of the cage.
He has a larger sized ceramic bowl for his water. Buns drink more water when they are provided a bowl than a bottle. I purchased a heavy ceramic bowl so that it could not be knocked over or slid around easily as buns are known for playing with their bowls. He does actually have a water bottle as well so that I know even if by some chance he spilt all of his water bowl he would still have water available.
I don't have a towel or blanket for Thumper because he chews a lot. Most people that provide their buns with a blanket will use fleece as it is safer for them if they happen to chew it than other materials such as towels.
Rabbits tend to go potty while eating so hanging a hay rack above the litter box is what most people do to help litter train and to help keep them litter trained. Or some just put some hay to one side of the litter box. I hung Thumpers feeder over the litter box and his hay rack to the front of the cage which has worked fine for me.
Thumper doesn't spook easily and with his size his cage space is limited. He seems to feel his cage is his safe place but if your bun is skittish or if you have plenty of room you could place a box in the cage that your bun can retreat to when it gets spooked or just feels like it.
You could also place some toys in the cage to help entertain your bun while it is in the cage.
Just a few suggestions. Hope it helps