In my experience, concrete (cinder) blocks make the best habitat. You can use nice pretty stone for the part of the shore line that people use. Then you can use concrete blocks below the water. Like anything else, these blocks might be available to you cheap or free depending on your situation. We get defective blocks for free. We throw the blocks into the lake in piles of 100-200. Small fish can swim in and around these blocks easily making them great fish attractors.

Norm Kopecky