- Three rectangular mirror planes.
- Join them together to form a prism.
- Fix them in a circular cardboard tube or tube of a thick chart paper. (The tube must be slightly longer than the mirror strips)
- Close one end of the tube by a cardboard disc having a hole in the centre
- At the other end, touching the mirrors, fix a circular plane glass plate.
- Small pieces of coloured glass are placed in this glass plate
- Close this end of the tube by a ground glass plate.
Allow enough space for the colour pieces to move around.