Thanks! We opted to buy cages since we have rudimentary woodworking skills, I doubt we could make something that would look nice enough, hehe.

We have been buying our cages from a local manufacturer that resells through local reptile stores, Critter Condos.

The problem with a young bp in a big cage is stress. They can get stressed out being a large environment. However, I would guess (and other more experienced members are welcome to chime in here) that you could use a 40G and put in a lot of hides and cage decor to give the snake lots of secure hiding places.