I have been trying to find a good natural method for rabbit tanning. I stumbled upon this on a forum.
I’ve had great results by first fleshing the fresh hide, then salting it for a week or so until it’s dried and hard (tack it flesh side up on a board and cover all of the flesh side with a layer of salt which usually takes about half a pound for rabbit hides). Then, take a knife and scrape all the salt off (it’ll be dried and stuck to the hide) and then buff the hide with sand paper to raise the grain. Wash the hide with warm water until it’s soft, then take about half a dozen egg yolks and work them into the hide the same way you would use brains. Keep rubbing it in and wringing the hide and working it back and fourth until the whole thing is dry. You have to keep it moving until it’s dried (usually takes a few hours) You’ll know it’s dry when it’s no longer cool to the touch. It works the same way as brain tanning (but it’s actually a kind of oil tan). Now all you have to do is smoke the hide to make it water resistant.