This head is based almost entirely off of a Solarbotics BEP Application.  It was made using BC1 and MD2 circuit boards along with a gearmotor I salvaged from a Bio-Bug.  The unit is controlled by the famous Wilf Rigter Solar Power Smart Head circuit.  For the base I used a big metal gear out of an old printer and super-glued it to the motor mount from the Bio-Bug's leg.  The antenna is a Bio-Bug tactile sensor.