Cut the two blanks for the tree sides per the cut list and Image 1. To help prevent tear-out along the edge, apply masking or painter's tape to the cut line.
Use the layout in Image 2 as a guide for marking the tree sides. A square is helpful in marking the diagonal lines. Be careful when marking the lines in the center of the tree. This center 3/4-inch-wide area is the slot where the two tree sides will intersect.
Use a jigsaw to cut out the excess areas on the sides and the center slots (Image 3).
Test fit the tree sides (Image 4). If the two parts are too snug, sand down the inside edges of the slots. Sand all edges and corners. Paint the upper area of the tree sides with dark-green paint, the bottom "trunk" area of the tree sides with brown paint.
From a 3/8-inch dowel, cut 80 berries, each 1/2 inch long. Use a hand saw with a miter box or miter saw to cut the pieces.
On each of the tree sides, randomly mark 20 spots for berries, and drill 3/8-inch-deep holes using a 3/8-inch Forstner bit (Image 1).
Paint the berries using red spray paint (Image 2). To make it easier, insert the berries in a foam-core board so they stand up in place. Punch holes in the foam-core board or use the 3/8-inch Forstner bit to drill holes.
Apply a dab of glue on the bottom of the berries and insert into the holes in the tree sides as shown in Image 3. Use a wooden or rubber mallet to tap the berries in place if needed.