This is an attempt to create a cel shader. In fact, it's more a gradient-based shading as you need to use a gradient to define what colors will be used to shade your mesh. Make sure to use at least one [PointLight] and adjust the Brightness and the light intensity. You can set the gradient interpolation to hold, but you can still use the other interpolations; then you'll have full control, for example, if you don't want hard edges between colors.