How would you build one? We might be interested.
EMP shield? First you have to decide what it is that you’d like to protect from a magnetic pulse. Big? Little? First, look up “Faraday Cage” to get a hint of the basics. Then think “lightning rod.”
Protecting something outside might first require building a tall pole with heavy wire to the ground. Then building a box around it strong enough to support a wire mesh cage, also grounded.
When you decide what to protect get back to us with the rest of your questions. There are knowledgeable folks hereabouts.
Build a box and wrap it with aluminum. Pretty easy if you can find thin aluminum sheets. Make sure and do the bottom first, place the generator on it then place the wrapped box over it.
-SB