I would say that Plywood works great. It is a bit more expensive than the melamine which would be an obvious choice for melamine, however, melamine is soo heavy... If your young like me and always moving, heavy snake cages can be a pain to lug around.

Here are a few photos of my current enclosures which are built out of 1/4" ply wood and 1" thick supports. Total weight is about 10lbs. So travel is a cinch.





Another thing to consider with melamine, is that it may need to be sealed to keep out moisture. This is easily done with plastic liners and such that are commonly seen on desks draws and cabinets. If you have ever spilled a glass of water on particle board you know how quickly it swells.

So in conclusion, melamine because its heavy and wont topple easily, durable if properly sealed, and cheap. But, I choose plywood because it is good too!

Probably more than you cared to hear but, that's why melamine.