1. Note: A 1-inch seam allowance is included in all measurements. Cut a 23×21 1/2-inch piece of burlap for the slipcover front and a 23x28-inch piece for the back. Lay slipcover front with a long edge toward you on a flat work surface protected with waxed paper; secure burlap to surface with painter's tape.
2. Referring to the photo, place the "I" stencil just left of center 5 1/2 inches from the bottom edge. Tape the stencil in place. Mix the acrylic paint with the fabric painting medium on a plate. Lightly dip the stencil brush into the paint mixture. Dab the stencil brush on the plate until the stencil brush is almost dry. Lightly tap the brush on the fabric inside the stencil until letter is covered with paint; let dry. Repeat to stencil all letters on the burlap.
3. Cut two 23-inch lengths each of ribbon and iron-on adhesive tape. Following the manufacturer's directions, use the iron-on adhesive tape to adhere a ribbon length 1 inch above and 1 inch below the stenciled lettering.
4. Press under 3 inches of slipcover front along the top edge. With the right sides together, place the front and back together, matching the bottom raw edges. Using a 1-inch seam allowance, sew the front and back together, starting and stopping at the folded edge of the slipcover front. Press the seams open, also pressing under 1 inch of slipcover back on unstitched side edges.
5. Turn the slipcover right side out. Fold down and press 1 inch, then 2 inches along the top edge of the slipcover back, and whipstitch in place using six strands of red floss to make the slipcover flap.
6. Turn down the flap and secure to the slipcover front, placing a hook-and-loop fastening tape square between front and flap on each side of slipcover. Sew a decorative button to the flap, and insert pillow into slipcover.