How to Build a Wooden Mirror Frame

Cut the plywood sheet to a size that measures 5 inches longer and 5 inches wider than the mirror for which you are building the frame. Use a tape measure to note the proper dimensions. Use a table saw to make the cut.

Cut a 1/4-inch-thick hardboard sheet into two pieces that measure 2 1/2-by-41-inches, and two pieces that measure 2 1/2-by-48-inches. These hardboard strips serve as the basic frame that outlines the mirror, and over which the finished frame mounts. Place the strips onto the plywood and check that all the pieces snugly fit together. Remove all the materials from the plywood sheet.

Spread a bead of wood glue on the back of each hardboard strip, and place the strips into position around the perimeter of the plywood backing. Allow the glue to dry according to the manufacturer's instructions.

Mix the epoxy cement according to the manufacturer's instructions, then spread some onto the back of the mirror in a staggered pattern that covers the entire surface. Fasten the mirror to the plywood backing in the center of the hardboard frame and allow the epoxy to dry according to the manufacturer's instructions

Lay the four 3 1/2-inch plinth blocks on top of the hardboard strips at each corner of the mirror frame. The blocks should overlap the edge of the mirror on the inside corner, and the edge of the plywood on the outside corner. Apply wood glue to the back of each block, and nail it in place with finishing nails driven into the hardboard strips and plywood backing.

Use the tape measure to record the distance between each corner block, and use the table saw to cut strips of 3-inch fluted door casing to size. Place each strip onto the mirror frame so it overlays the mirror by about 1 inch and so it lines up at the center of the slightly larger corner blocks. The result is a mirror frame that slightly bulges at each corner, and that covers the mirror edge all the way around.

Apply wood glue to the back of each casing strip, and use a hammer and finishing nails to fasten it in place the same way as the corner blocks. Use wood filler to seal any visible nail holes on the surface of the frame. Allow the wood filler to dry according to the manufacturer's instructions. Use fine-grit sandpaper to smooth it all over.

Use a paintbrush to apply paint.