I posted an older thread about this, asking about fibreglass + epoxy resin, but I would like alternative options. I would rather use a natural sealing method, but usually those aren't as durable or long-lived. My favourite so far just from reading about all the different options is tung oil or Danish oil, but then longevity comes into mind and I think marine spar varnish. I want an enclosure with a bioactive substrate, so it would be in perpetual contact with moist soil and anything going through the soil, with royal python conditions. Aside from being durable, of course I want it to be safe for the inhabitants (plant and animal) and not leech any petroleum-related hormones and whatnot. I've chosen white oak for the wood.
My other concern is with the ventilation. I just read in another thread about not making them near the top of the cage, in order to retain more humidity and warm air, but in a tank with live plants and a bioactive substrate, I want to replicate natural conditions for the sake of all the associated processes. Would it be a noticeable difference in resource usage (electricity and water replacement), placing the vents a few inches lower, and would it have any noticeable effects on the contained ecosystem? By the way, I know using live plants in a python cage may not be the best idea for the plants, but I'm going to do lots of research on very hardy plants and they'll be well-established before the snake goes in.