Large picture frames can get quite expensive, especially if you need to frame an artwork that is of irregular size. Making your own large frame will enable you to customize the size to your exact needs, as well as maybe deducting from the cost of a store-bought or custom-ordered frame. Using pre-made frame molding, available from most framers and lumber yards, will make the picture frame project a quick and easy job.
Cut two pieces of frame molding to the length of the desired frame, and two to the height. Cut the ends of the pieces of molding to 45-degree angles on a miter saw, with the angles oriented inward and at opposing slants, so that when joined together, the angles will make corners.
Apply a smear of wood glue to the ends of the frame planks, and then form them into a frame by mating the mitered corners, ensuring the decorative sides of the molding are on front, and the side with the glass and mounting board groove are at the back. Place the frame in corner clamps to dry; approximately an hour, depending on your wood glue.
Hammer in two finishing nails through the sides of the frame into each corner joint, so there are four nails per joint altogether.
Fill the nail holes with putty and leave to dry, then sand the frame and stain, varnish or paint it as desired.
If frame molding is unavailable, you can make your own using a router. Create the decorative side as desired on the front of the lumber -- 2-by-4 inch lumber is ideal -- and route a groove on the inside edge of all the frame planks around 1/2 inch wide and 1/4 inch deep for housing the glass and mounting board for framing.
Regular construction molding, not crown molding, can also be used for a picture frame. Simply cut in the glass and mounting board groove on the back and use like frame molding.