Tin-foil hats: What is the most effective way to make them?

Question

By effective I mean making tin-foil hats that keep the Government from messing with your head. And don't try telling me they don't.

Answer 1

There was a study at MIT of three different types of hats.  See link below.

Answer 2

A smooth dome shape on the outside with a crinkled interior.  The smooth dome will deflect most waves and the crinkled interior would redirect them should they penetrate the outer shell.

Answer 3

With tin foil. I don't think aluminum is as effective.