While plywood is most often installed as an underlayment and is typically covered with something on top, it can be on the surface of areas, such as porches and certain walls of your house. Since most plywood is not tongue and groove, when it is installed, the pieces just butt together, making the seams look unattractive. You can cover up these seams in the plywood with just a few materials and have it looking like one continuous sheet.
Sand down the plywood, particularly around the edges where the pieces meet at the seams. Go over the entire surface with medium-grade sandpaper in a circular motion. Continue until all of the seams have been sanded down and the surface is smooth throughout.
Wipe down the areas where you sanded with a clean rag. This will remove all the grit left over from the sandpaper and leave a smooth surface for the edging to lay on. Dampen the cloth with water and use dish soap, if necessary to remove the dirt and grease from the surface. Let it dry completely.
Measure the length of the seams between the pieces of plywood. Most seams will measure 8-feet, if the plywood is installed vertically. Cut pieces of veneer edging material off the roll that are 8-feet in length with a pair of scissors.
Flip the first piece of veneer over and run a bead of glue along the center at the back of the piece from one end to the other. Line the edging up over the first seam and press it into place by hand. Run your hands up and down over the entire surface so it can adhere in place to the plywood underneath.
Install the next piece of veneer edging and all of the remaining pieces in the exact same manner until all of the seams have been covered.