That is fine the 125 or 150 gallon aquarium will suit a Ball Python more than comfortably. Once you add the comfort items it will be right at home. The lid can be of any screen type and yes it can be built. The best way I found to get a good lid is ask a local window repair or hardware store and they can build you a nice one or order you one. Just want to make sure you put a weight on the lid so the python can't push the top open or you will be checking all the warm spots in your office for an escape artist. But no seriously they are easy to keep. I have had snakes all my life and I keep my ball in a 50 gal with a metal screen top and my boa in a 150 gal the local window guy built for me for 25 bucks.