You'll need five sheets of 3/4" x 4' x 8' plywood, one rubber mat 3/4" x 4' x 8', and a box of 1.25" drywall screws. Don't use glue -- Murphy's law says that you'll need to move the platform right after the glue sets. This platform weighs over 400 pounds! Don't use glue, okay? Screws are fine.