I had one in California. It was built with 1/2" plywood insulated with 6" fiberglass on the inside, except the floor was 4" of rigid foam with a piece of vinyl over it. Look for the batts that are completely wrapped in plastic. If you use them, you don't have to worry so much about tight seals.
I started with a 36" square and insulated that down to about 24" inside.
Used a 200 watt space heater with a fan and a Ranco controller.
Don't have any pictures, though.
If I was doing it again, I'd use that fake tile (for showers) board for the interior. Real easy to clean.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk
Last edited by david_42; 12-15-2007 at 02:43 PM.