Re: Plywood Vivariums??
This topic has been discussed at some length here over the years, by me and others. I suggest more research, fewer questions for the next few days. Then come back, OK? Meanwhile, to summarize:
I've made a half-dozen large plywood vivs. Most are still in service - one I demolished for a few reasons that all came together at once. Another - just one - I demolished because I hadn't sealed it well enough at the drain penetration, and it was molding badly. I also came to dislike some of the features I had put in, and wanted some I'd left out.
That latter example was my very first one. I had tried to seal it with about 3 coats of Drylok, and - where the water was - some Polygem 307-Lite putty. Subsequent builds have also featured an initial Drylok seal (multiple coats) and either one of two epoxy products, in at least two carefully-applied coats: the Polygem putty, or Habitat Cast-n-Coat brushable / flowing (but thick, like cool honey) epoxy. I've never used anything from West, or from Pond Armor. I'll probably never use the West for a viv - so runny, just looks too easy to mess up. But I can easily see myself getting one of the colors of Pond Shield some day.
It is a lot of work; operator error is a distinct possibility - that's what doomed my first build, I'm still using the exact same materials and they work great when you do it right. I find the work itself mostly enjoyable and rewarding. I find the product and its performance, when successful, to be supremely gratifying. If you do it right, the product is effectively immortal. And wood is just so easy to work with. I've got the tools, I've developed adequate skills, I can get the results I want.
Optimization is about minimizing or maximizing ONE THING, and dealing with tradeoffs of all the other things you might value. If you want to minimize dollar cost, well, do that. In building plywood vivs I sought to maximize enclosure excellence for my specific application. Nothing off-the-shelf even comes close - to go that route would be to minimize expended time and effort (and sacrifice quite a lot of function). I have bought numerous xPVC, glass, melamine, and fiberglass cages for snakes (desert to jungle) over the decades. Often these bought ones can be modified to improve performance; but when I build my own, I get the size, shape, and most importantly, all the features & design specs I want.
As for cost - with experience, I can now build a large custom plywood viv for about the cost of something I can just order and get delivered. So it is not really cheaper, and it takes a fuck-ton more time. But I get what I want, which has really never, ever been the case with cages I have bought. And I have bought MANY cages. Again - for what I do, the way I want to do it - none have ever really worked like I wanted. Eventually, they let me down or left me wanting. All this is what has helped inform my own design and performance specs.
If you are interested in building a plywood viv, I recommend you bite the bullet and build a scaled-down prototype (or two...) you never mean to put in actual service, but that maybe you use as a plant grow-out tank or something. A crash-test dummy, if you will. Test it hard, crash it hard. Trust me, you'll learn a ton from the mistakes you would rather not make in a real working viv. There's no getting around the learning, you have to go straight through it. What you can control is the consequences - will you have to inconvenience your animals, and yourself, by needing to replace their home - or will you avoid that?