Buy nine 6 foot 2 by 4s, three 9 foot 2 by 4s, forty 6 foot 1 by 4 decking planks, 3 inch wood nails and 2 inch wood nails.
Make the deck feet first. They will keep the structure a few inches off the ground. Cut 9 foot 2 by 4s into six 18 inch lengths. Using 2 inch nails, fasten two of those together to form nine individual feet for your deck.
Cut the lumber. The deck's four modules, when completed, will measure 12 feet long by 70 inches wide when placed together. For the modules, cut five 6 foot 2 by4s into ten 3-foot lengths. Those form the ends and the support members. Four 6 foot 2 by 4s will be the sides.
Using 3 inch nails, secure two 3 foot 2 by 4s to two 6 foot 2 by 4s to form a rectangle. Now do the same to form the other three rectangular frames of the modules. Nail 3 foot 2 by 4 support members in the middle of the module. The supports will run across the width of the section.
Nail the 1 by 4 decking to your frames using 2 inch nails. Drill holes for your nails before you pound them in. Use the width of an extra piece of decking, held vertically, to provide space between the decking planks. Space is needed for water to run between decking and onto ground.
Turn modules over and nail on feet at the four corners of each module. Use 3 inch nails. When you finish, turn modules upright and place the four sections together to form deck. Walk on deck to make sure it is solid and stable. If you feel any wobbling or weak areas, check out the underside to see if you have made errors or if the feet are stable.
Stain deck the color you like. Use at least two coats of waterproof stain. Stain is preferable to paint, which will wear off.
Store modules in camper for your next trip to the woods.
