Decide on your design and size.
Using a circular saw or a miter saw cut all of the pieces of oak trim to length.
Using a circular saw or a miter saw cut a 45-degree corner.
Using a table saw, set at a one-half inch above the table saw height and run the wood through/over the table saw to create a groove. This groove will be where you slide the plexiglass and artwork for display.
Dry fit the frame together and make sure everything fits.
Use wood glue, clamps and brad nails to attach the frame together. Remember, you do not want to attach the top piece.
You can choose to add extra support of wood across the back of the frame for support and for a place to put your sawtooth holder. Use the brad nailer and wood glue to attach this.
If needed, use a jigsaw and a fine-tooth blade (metal blade) cut the plexiglass. Check fit of plexiglass in box.
Apply and wipe stain. Let dry for 24 hours.
Apply spray on poly and let dry.