LED 12v 5 metre waterproof with choice of colour/fades and sound activation. The sandstone is 20 quid a tonne and can be picked up from Leighton Buzzard sand pits in a van/car. Though you will need a sledge hammer to break off the good bits. I used half a tonne! Pond liner is self repairing and I laid it on a thick orange membrane which was then bedded on sharp sand. The pond today is 8 years old and has plants/moss growing on it. The lights still work and the fish can now Breakdance Lol.