Timus

Hi! New member here so please bear with me.. I need a device that will randomly flash a set of 7 lights (the bulbs can be 3.5 or 12 volt). I would like the timing of the flashes to be random (anywhere between up to, say, 10 seconds) and for the number of lights lit to also be random. I really have no clue where to start with this - would I have to build something or can I buy something that will do the job for me. I would be very grateful for your advice! Thanks all, Tim