Step 1: What You'll need
1 inch PT CDX plywood half sheet
2 lbs 3 inch deck screws
2 lbs 2 inch deck screws
Pocket hole jig (optional)
Drill & bits
Assorted woodworking paraphernalia (clamps, cords, etc)
Most of this stuff I had laying around, the wood came from disassembled garden boxes from our previous residence, so I can not give an accurate board footage used. Fasteners should be chosen for compatibility with PT lumber.