Range finder electronics


New Hunter
Hi there.
I was wondering what sort of electronics board people use to create the flashing lights on their range finders.
I have built one and found a small board in Maplin that allows me to create a alternating flash but i cant do any random patterns which would make it more realistic.
I have all the other items ie battery power, holders, GOW bulbs (6v)

Any help for a UK based person would be great thanks