45 minutes
Cut the long piece to 21", then crosscut the two end pieces to 4". I measured up the long piece 14" and 18" (ignore the measurements in the photo) , that is the end piece placement location. I used a biscuit joiner and a #10 biscuit plus glue to join everything together. Since the material dimension is 21″ × 16.5″ , I fudged that size by using a scrap piece of 1″ × 6″ and placed it to the left of the work piece to set my zero and Z probe.