A google search will yield plans for several different designs. These are nice to make the best use of materials and to know what supplies to get. I like double walls with foam insulation between them. Quieter and warmer. Can be metal exterior and plywood interior.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli