Well, I personally just take pieces of old dead rock, and smash it with a hammer
whatever pieces look nice i rub the edges together in water to smooth them out, and viola, free frag pieces. I have heard of the golf tee idea, though I would avoid the wood, as it's going to rot over time, and you certainly want whatever coral your fragging to have a solid base. I would say go with the plastic if anything! Just remember the rubble doesn't have to be live to glue frags to it... ceramic and golf tees sure as heck aren't live
