I’ve built from scratch, converted bookshelves, and reworked a store display case. The biggest hurdle is to get everything well sealed so that wood or particle board doesn’t get wet. Melamine shelves only need the seams sealed, bare wood would need the entire surface sealed. Bookshelves were the easiest for a multiple enclosure setup, but a cabinet with shelves should work. Radiant heat panels would probaby be the best and easiest heat source. Heat lamps or CHE also work, but you have to make sure there is a cage or screening around them that will prevent your reptile from getting burned.