Suggest a method to produce a rainbow in your house.

The principle behind making a rainbow is to disperse the white light. One method to make a rainbow inside a room is to allow a narrow beam of light to fall on a surface of the water in a glass. For this sunray is allowed to make a narrow beam from a partly closed window. Transparent glass is filled with clear water and a paper with a slit is glued to the upper portion of the glass. The glass is placed such that the sun rays fall on the slit and the emerging light is allowed to fall on a white paper. We get a rainbow on the paper. See the diagram below.