PVC enclosure help

[baker247365]

I wanted to have a 3'x5'x3' (DxWxH) enclosure with a second level to maximize square footage. I got a quote to have it custom made but the cost is way out of my budget. I'm going to try to make one myself but have a few questions.

If it's 5 feet wide, how much support/cross bracing am I going to need?

Is it easy to use a router to make cutouts for windows?

 

[wellington]

What species is this for and how big?
An adult Russian needs a minimum of a 4x8 foot. Are you trying to reach that with having the second level?

 

[baker247365]

What species is this for and how big?
An adult Russian needs a minimum of a 4x8 foot. Are you trying to reach that with having the second level?

Yes, it's for a 1 year Russian and yes, I'm trying to get close to the 4x8 sizing. I can get 30 square feet with the design I have so far and he has a wheel right now that he loves so it should be good for awhile I think.

I looked at 5/8" thickness cellular PVC sheets today and was surprised at how floppy it was so I'm mostly wondering how much structural support it's going to need.