It seems to me that a microwave oven is a faraday cage. If I cant find an old one big enough to cram the TV and the box into, I would think I could take apart an old one and figure out how to incorporate parts of several old ones into one faraday cage.
When you build your Faraday cage, remember it needs to cover all the way around. It should also be grounded at a single point. The tricky part is being able to move power into the cage to run stuff without providing a leakage path. Feed-through capacitors and series inductors will play a part in doing that right. The door will typically need something called "finger stock" to provide a slightly spring-loaded conducting path all the way around. The largest Faraday cage I've ever worked inside was designed to keep the EMP from a nuke weapon from destroying the computers inside. It is tested weekly.