The 45 degree sloping bottom divides the glass in two triangular sections. When the glass cup is filled with water, the top section becomes a water prism that allows passing sunlight to project a rainbow on whatever surface it rests on.
Your designs can spark a whole range of emotions in people. Color theory unlocks the secrets of how to use hues to inspire joy, sadness, and even hunger. -- or, you know, make art or not to have clashing colors.