Things You'll Need
Plywood, 1/4-inch-thick marine-grade
Styrofoam, 2 inches thick
A freezer box can reduce the amount of electricity a home or cabin consumes by keeping food cool next to a block of ice, rather than using condensed freon. A freezer box can also be useful in places with limited access to power, such as a boat or camper.
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Cut the plywood with the circular saw to the following dimensions: two sheets 24-by-24, two sheets 28-by-28, three sheets 36-by-24, three sheets 40-by-28, one sheet to 42-by-30.
Nail two of the 40-by-28 pieces together with the 28-by-28 pieces to create a rectangular box. The 28-by-28 pieces will fit at the ends, with nails going through these boards into the ends of the 40-by-28 pieces. Nail the third 40-by-28 piece to the top of the rectangle, putting nails through the board and into the ends of the other four boards.
Use a utility knife to cut the styrofoam board. Cut three 38-by-26 pieces and two 26-by-26 pieces. Place the pieces of foam into the plywood box you just made -- with the 26-by-26 sections inside the shorter ends -- pressing them firmly into place. The pressure from the other styrofoam pieces will hold them all securely.
Nail the three 36-by-24 pieces and the two 24-by-24 pieces together to create a smaller box, in the same way you made the larger box. Put this smaller box into the styrofoam layer you just put inside the larger box. It should fit snugly.
Cut a piece of styrofoam to 42-by-30. Nail it to the 42-by-30 piece of plywood to create an insulated lid. Add ice to the inner box, put whatever you want to keep cold inside and lay the lid on top. The weight of the lid will create a sufficient seal.