Sale is one thing, but possession and use are a separate thing. If you happen to build a faraday cage on your own private property and want to run some sort of

Sale is one thing, but possession and use are a separate thing. If you happen to build a faraday cage on your own private property and want to run some sort of thing that is a jammer within it the FCC isn't going to come after you. It's intentional radiators they care about. What you can't do is operate a business and fill the lobby for example with jammers that wipe out cell phone service and then require people to pay for access via WiFi.