Made by attaching thin sheets of veneer or wood together, plywood is a viable choice for woodworking projects both indoors and outdoors. Cabinets and furniture pieces are just a couple of things you can make with plywood. Combining sheets of plywood makes the wood project more durable. Voids in plywood are simply large holes that occur naturally in the surface of the wood. While it's best to fill any voids prior to attaching pieces of plywood together, you can fill voids between plywood sheets with wood filler.
Sand the surface of the plywood with 80-grit sandpaper.
Combine wood filler with some of the sawdust in a small container. This ensures the color of the filler matches the plywood.
Fill a syringe with the wood filler. You can find syringes at woodworking shops or home improvement stores.
Lift the edge of the one sheet of plywood until you can insert the syringe over the void. Inject the filler into the gap and fill the void until the filler is flush with the surface of the wood.
Apply a layer of adhesive on the surface of the bottom piece of plywood. Clamp the sheets together overnight while the adhesive dries.
Fill voids on the outside layer of plywood by inserting enough putty to cover the void. Use a putty scraper to smooth the putty flush over the hole and wipe away any excess.
Rub the outer surface with the sandpaper to blend the filled hole to make a smooth surface. Sand the edges for a smooth finish. Wipe away sawdust with a tack cloth.