I think that falls in a "it's not illegal if you don't get caught" scenario -- that is, unless you make an incomplete Faraday cage, the FCC would have no real m

I think that falls in a "it's not illegal if you don't get caught" scenario -- that is, unless you make an incomplete Faraday cage, the FCC would have no real means to catch you doing that. Also, since you wouldn't be jamming anyone else's signals, nobody would report you. You'll find out real quick if you screwed up your Faraday cage design, though.