Hi lilith!
both of our enclosures are sealed timber, 1 a recycled bookcase and one an mdf (okay not real timber) ready made.
We just went to Bunnings and read every label and discussed - sometimes a bit loudly and emphatically! (ie argued) - until we found the most non-toxic waterproof environmentally friendly slightly tinted lacquer we could find. I'm sorry I can't remember what brand that was either, but I believe we went for one that had a water clean up rather than turps, usually these have less residual odour and are less toxic than turps clean up IMO but more than willing to be corrected on that one

Hope that helps

cheers
Cat