The Surfboard is made from standard pressure treated wood. Because wood will warp and bend, the 2x6 boards that make up the surfboard are spaced 1/4".
The base of the shower has thick layer of stone pebbles.
The pluming is easily done with PVC pipe. To keep the project cheap, PVC faucet - ball valves were used and fitted with wooden knobs. The shower head is made from a 1" PVC pipe where several tiny holes were drilled.
Because it is an outdoor shower it is convenient to be able to just wash your feet. This is done with a horizontal pipe with holes at an angle about 12" above the base.
The sides of the shower are also made with pressure treated wood and the slats are spaced 1/2".