Dont jump on my case because you dont know US laws or how the country's laws work.
Are you joking or just stupid?http://www.fcc.gov/search/results/jamming
When you can find laws prohibiting sales of such devices with body text that says
Signal jamming devices pose significant risks to public safety and potentially
compromise other radio communications services.
Then you should be able to figure out that building your own is not an 'out'. Whether you buy or build you own gun, if you shoot someone it counts.
Your examples/exceptions are a joke BTW.
If I caused enough interference to be noticed, the FCC would let me know and fine me. That's not guesswork either. My circuits don't run enough power to compete with my open-box PC and it doesn't cause noticeable interference to my TV or radio.
There is such a thing as _proportion_ and in the case of interference it has to reach far enough to be detected to matter. You don't seem to know the difference between what matters and what does not.
Will your jammer be so short-ranged as a normal PC, or short in an appliance or some low power Arduino project I make? Or will it be powerful to jam FM radio signals at any useful distance?
"Mommy I want a cookie."
"Not until you eat your food."
"But cookies ARE food!"