A semi-ellipse of colour-effect filter glass projects perpendicularly from a white rectangular plane that resembles a door. Light is projected onto the glass from a bucket located below, which is half-lidded by a semi-circular cap. The colour-effect filter glass reflects the shorter light waves, forming the blue bottom half of a circle, while the longer waves are allowed to pass through the glass, forming the yellow upper half of the circle. Although the shape of the filter glass is a semi-ellipse, it has been installed in relation to the light source so that the reflections above and below the glass distort to create a perfectly round two-tone circle.