flasher relays?

can anybody tell me how a 3 pin flasher relay works? and how i could make my own flasher relay out of a standard autmotovie relay.

If I remember this right- X= power in, L= load (the turn switch) and P= pilot (indicator). What happens is the flasher is made up sorta like a spst switch, but the contact arm is made of a layered material- a bimetal- which when current is applied from x to l, heats up and acts exactly like a circuit breaker. Because of the construction, you cannot, as far as I know, make one from a standard relay. The 2-pin flashers work exactly the same, except they do not have a pilot output.