For some building projects plywood sheets may need bending or warping. Plywood, when left out in the elements will warp depending on what is underneath it as gravity pulls it down and ambient moisture gives the plywood malleable qualities. If you need to hasten the warping with some plywood sheets, steam the wood and fashion the warp into the shape you desire. Wear suitable heavy duty gloves to avoid any steam burns.
Place a metal drum in a fire pit or fireplace area in a yard or other outside region. Fill the barrel two-thirds full of water. Start a fire around the barrel and bring the water to a boil so that steam comes out of the top.
Place the metal grate or grill across the top of the barrel. Put bricks or objects on top of the grill on which the plywood will be placed. The plywood, as it gets steamed and wet, will warp and bend on the bricks or objects.
Place the plywood onto the grate and bricks. Leave it over the steam for at least 30 minutes. Do not leave the fire unattended. Check the warp on the plywood and remove it when reaches your desired bend and curve.
Spread out the tarp on the ground and place the plywood on it once the warp meets with your needs. Leave the hot and warped plywood on the tarp until it has cooled and is dry. Place the bricks and objects under the plywood and on the tarp to keep the bends in the wood as it dries and cools.