Well, actually, I see four cages there , add some material to the back sides will help width , one of my go to Trixx is to add polystyrene fluted panels to the inside . Silicone edges and spray flexseal over the top. To make it watertight on the inside. Doors are always an issue with Wood but if sealed properly, they can last you a long time make sure to use stainless steel or plastic. Hinges because that’s also an issue. Proper drainage will help maintain the longevity of a wood enclosure . I would also try to provide doors or ventilation low , or something you can open and close to control humidity . It will either help create a chimney effect or adding computer fans
To keep air movement. Foggers are a great way of keeping humidity levels in as well as misting systems. All of this requires proper drainage. Take all of these things into consideration when starting your project make sure to leave room for it .. remember, regular maintenance is is definitely going to come in to play so make things easy to work on . good luck on your adventure. It’s fun to build your own.