In my experience, the best way to get a rabbit to tame down is just to hold them as much as possible. Don't let the struggling or nipping affect you; if he nips and you put him down, he learns that nipping gets him what he wants. I have accumulated tons of scars on my wrists and arms from being scratched by rabbits, but I have never put one down because it scratched me. If a rabbit I'm holding starts to struggle, I simply hold it more firmly (without squeezing it or hurting it), adjust my position a little so that hopefully it feels more secure, and don't put it down until after it's stopped struggling. Once a rabbit learns that struggling isn't going to get it anywhere, it'll usually become pretty easy to handle (so long as it also feels secure when being held). I see so many people act like they're scared to death of getting scratched by this 3 lb. bunny they're holding. A scratch or nip isn't going to kill you, or even hurt for very long. It's something you will have to deal with if you have a rabbit, no matter what. Just get him out and hold him several times per day. Sit down with him in your lap and stroke him (most rabbits I've known enjoy having their heads rubbed or scratched gently). If he struggles, don't put him down until he's stopped (unless you feel like you're absolutely going to drop him if you don't put him down). Once he's stopped struggling, stroke him a little longer and talk softly to him, then put him down, so that he doesn't associate being put back down with his struggling. This method of taming has never failed me in the 17 years that I've owned rabbits.