There are a lot of different materials you could go with. There are some excellent examples in this DIY subforum. If you want something that will be sturdy and last, stick with hardwoods like oak. Avoid soft wood like pine or spruce. Oak will be heavy so using something like a nice quality untreated plywood or bamboo sheets would work well. People usually seal with either a couple of polyurethane coats or a non toxic latex paint. Do be sure to build your enclosure large enough for an adult to have space. 4x2x2' is often discussed as the minimum, but you could build up taller or larger if you have the space to do so. Since you need two of them, a stackable setup might work best and save on space. If you have the room though, you can build individual tanks to sit side by side or nearby. A lot of it comes down to personal preferences really. I suggest browsing the Enclosures and DIY subforums to get some good ideas.
