Distribute cucumber slices on a platter and scrape out seeds from the middle, leaving a deep hole (but don't scrape all the way to the bottom). Fill hole with ranch dressing and spread a little on the rim, so bell pepper will stick. Distribute green bell pepper around the rim to look like a wreath, leaving one spot empty.
Cut out small bow shapes (figure 8s) from the red pepper with a sharp knife and cut two thin strips for the ribbons. Place "wreath" on the cucumber slices.