Is it safe to paint the inside of a rabbit cage? Will it be poisonous if they eat it?
I hope you know that rabbits will eat any wooden surface that is not flat. Once there is an edge, they’ll eat it up with time. So the best thing to do is to cover them with metal sheets like the ones from milk cans. You can also cover them with wire mesh thick enough not to be chewed through. Don’t paint, it can be poisonous.
You can paint it but make sure the rabbits don't have access to it.
Treated wood will last longer, but if they eat it they can get sick.