I immediately thought of a boing ball stencil also, but I'm afraid to make holes in the case and let out all that RFI. Most computer cases are really quite good at shielding, but holes in the case or unsealed seams, etc, all increase the leakage level. If you are trying to listen to weak radio signals as well, you don't want holes in the case of the computer. And when you have eight computers in the house, all running at once, HF and VHF noise are a real problem.
tony
