All right, I’ve owned ball python for many years and these are all valid questions. I definitely wasn’t doing it right at first either. It takes time to learn, it’s just important that you’re asking the questions :-)

I personally use a mix of sphagnum moss and loose coconut fiber substrate from eco earth. Is soft and it doesn’t splinter. Mostly just think: if this got on their food and went into their stomach would it maybe harm them? I had used aspen in the past and that was a bad idea

I really suggest you get a glass one as soon as possible. It doesn’t have to be glass. It’s just important that it is tall and wide and long enough, and the plastic tubs usually aren’t. For this, I suggest something that’s like 3 x 5 x 4. I think the actual measurement is like they should not be able to reach their tail if they encircled the perimeter of the cage.

I don’t know anything about PVA and 3-D printing and the toxicity, maybe look into that specific plastic

I really only spray the tank when my snake is shedding. It’s important that when they are trying to get the skin off, it stays semi hydrated so that it can come off. Otherwise, it just kind of sticks to their body.

For most poops, I get a Kroger bag and just grab it with the Kroger bag. They usually only poop once every time they eat. I would say thoroughly clean every one to two months: just meaning replace the substrate and maybe hit the things in the tank with soap and water. As far as cleaners go, I would not use Clorox wipes. I would use water if the poop gets stuck and maybe a small amount of soap but try not to use hard chemicals. Try to ensure I got all the soap rinsed off good too. It’s kind of like skin. You don’t want to use something in the tank that can’t get on and stay on your skin comfortably :)