Cover the wood with white paint. Use the largest paint brush you can in order to cover the largest amount of wood at one time, but try to work in one 6-foot-square area at a time to give the look of marble sheets or panels. Allow the paint to dry for 1 to 2 hours.
Dab a light coating of cream paint on the wood to create a variance of color. Smudge on the cream paint with a dry sponge in a random manner and allow the cream paint to dry for 1 hour.
Brush brown paint onto the wood. Use a detail paint brush to draw Y-shaped lines in a mixed order over the surface. Smudge the brown paint with a dry sponge to create more depth in the marbled wood's appearance. Allow the paint to dry for an hour.
Paint grey lines onto the wood using a detail brush. Draw straight lines and Y-lines across the surface, mixing up the painting direction from vertical to horizontal spontaneously. Smudge the gray paint with a sponge to create more depth. Let the paint dry for 1 hour.
Paint black lines over the wood. Draw straight lines and Y-lines across the surface, mixing up the painting direction from vertical to horizontal spontaneously. Use a fine detail brush to create hairline designs across the wood surface. Allow the paint to dry for 1 hour.
Cover the wood surface with spray-on polyurethane clear coating. Shake the can vigorously for 1 to 2 minutes, and then hold the can 10 to 12 inches from the surface when applying. Allow the finished surface to dry for 24 hours.