Hi! Be sure to post some pics when your new bun arrives . The hideaway is perfectly fine as is. It looks like the litter box is a disposable? That might get a little expensive replacing them all the time, plus your bun will probably chew on it and destroy it. May I suggest a washable plastic one? You can use litter boxes made for cats, just make sure at least one side for entry is not too high so that your bun can hop in it easily. You don’t per se need a liner for the litter box but you can use newspaper to line it, and the litter box does need bedding – paper clumps (ie. Carefresh) or shavings (just not pine shavings) – which will soak up urine and assist with odors. Since buns eat and use the restroom at the same time, hay in the box is good, but you don’t have to spread it everywhere (ie. placing a pile of hay on one side of the box). For instance, Luna’s litter box is right in front of where her hay rack hangs, and any hay that falls out just lands in the box on that side. She eats the hay from both the rack and the hay that lands in her box.

I would avoid using litter box liners with rabbits. Mainly because they will likely chew them, and the absorbent material that is often in these liners, not to mention plastic in general are very dangerous for a bun to ingest. I would be using litter in the box, I use wood pellet litter (sold as wood stove pellets, horse stall bedding, or cat litter), many people also use compressed paper pellets or carefresh, but I find the wood pellets more economical and much better at odour control.

The cardboard borders are safe Some rabbits like to shred cardboard which is fine, however if they ingest a lot of it at one time it can lead to blockages, so just keep an eye out for that.

The door on the house will be fine, you could have certainly made it smaller but it won’t be too big. I prefer to make the doors on my cardboard houses a little on the small side because then my bunnies love adjusting them to their desired dimensions