My lamp base creations are constructed of natural driftwood which I have found or bases which I have made using cedar, cypress or other natural wood. Wood is my preferred material as it complements naturally occurring sea glass.
Metallic bases may be used as well. Granite forms the substructure for most vertical wood bases.
Lighting is usually a single bulb for most lamps, and 40-watt is most common. I prefer to utilize an in-line switch to minimize contact with the lampshade itself. This is easily adjusted by the wishes of the client.