Lord knows I’m no expert, being a new bunny mama, but I agree with these guys. When I first brought my 2 month old home, he was in his cage with a litter tray underneath and a litter box in the corner. The first day I noticed he picked a different corner to pee in, so the next day I rearranged things and put the box there. I would go in and visit him, just opening the cage door and putting my hand inside for him to sniff and get used to.
After a couple days, and noticing he was peeing in the box, I opened the cage door and put a set of improvised stairs in front of the door so he could explore if he wanted (jigsaw puzzle boxes taped together with duct tape!). He started coming out of his cage and hopping around, and I would sit still and pretend to groom myself and I would lie on the floor at his level and wiggle my nose and blink at him. Even though he had a second larger litter box in his room (pretty big, 7’x14′) outside his cage he would just lie in it, dig a bit, and eat hay but never pee. He would always hop back inside his cage and pee, and when he would go in voluntarily, I would usually shut the door after him if I was done visiting with him, that way I never had to seem aggressive and actually pick him up to put him away. I waited until it was his idea, like he needed a drink or food. If all else failed I would put fresh pellets and hay in his cage and he would happily go check it out.
After a few more days, I started leaving the cage door open all the time, and I would bring fresh veggies in with me during my visits. He got really friendly really fast, and still would always go back in his cage to pee. I don’t know if I got lucky, or if he is the world’s smartest bunny, but I am so happy with his potty performance. I think if he started to get messy or go somewhere else, I would definitely start confining him to his cage when I’m not there with him and I would clean the accidents with vinegar and water right away. A couple more tips – I put a canvas painter’s tarp over the entire carpeted floor, then I bought a piece of remnant linoleum from a local flooring store for $10 and put it under the end of the room where his cage is. This is where I sit when I feed him his fresh veggies, because when I want to pick him up and cuddle him, he can scramble with his feet for a second until I get him lifted right, but he can’t get any traction and go anywhere. It makes him believe I can pick him up anytime and he has become okay with it and really doesn’t even struggle anymore. In fact, it seems like he likes it.
Good luck!!! And, thanks for posting your challenges. That’s the best part about this board is we learn from each other.