We used to do this all the time when I was a kid. We would get stereos, tv's cabinets, just about whatever we could find in the trash heap. We'd gut em and add acrylic or glass. For terrariums we'd add some lighting and a thermometer including transformers and relays to operate the lighting to keep temps stable. It helped that the neighborhood I lived in had some smart woodworking dads and some refrigeration dads that showed us how to do it a few times before we made them ourselves. We'd scour junk piles once a month and visit the TV repair shop. $10 bought us those old time wood TV's. Times are changing and those haven't been around for decades. Kinda scarce. It's a really simple process to pull off, especially working with acrylics as you just cut the panels the same dimensions as the inside of the cabinet and using an acrylic solvent and a syringe fill the seams with solvent. Today's nice bowfronts could add a dimension of realism that we did not have as kids. The bowfront tank would look like the old picture tube. You could have filtration issues as most canisters would be out of hte picture and you probably wouldn't want a HOB type filter keeping the cabinet out from the wall. Using acrylic would be an easy way to design an internal overflow with wetdry built into the back of the tank. Many acrylic manufacturers already do this with their tanks. Also do an internet search for "macquariums or mac aquariums" You'll find hundreds of threads detailing the old Apple Mac shells as aquariums and how to instructions. You might even find an old Mac on Ebay. The shipping would be a lot cheaper..