When I first got interested in robotics Beam was where I turned first.  Their idea of complex behavior with minimal parts and no programming got me interested in a big way.  They made the coolest stuff out of junk, walking insects, phototropic bugs and heads, just neat stuff in general.  I started with high hopes of making a 4 legged walker and my initial design came along very nicely except when I attached the two motors I realized that direct drive did not have enough torque to turn the legs.  I had a hard time finding geared motors that were inexpensive and about the size and shape I needed so off to the local electronics store.  Never did find what I needed but I did hookup with some really nice low power consumption motors that could be driven right from a chip like the Bicore.  So I started playing with light-following heads and got some decent results.

(All the Capacitors are .22 uF)

    My first design barely fit on a 2" by 2" prototype board and well... looked pretty ugly.  After all the A in BEAM did stand for Aesthetics.  But it worked and that was encouraging enough.  So I started looking at what other people had done and didn't see much about phototropic heads.  While doing that I ran across a page where this guy had made very nice complex frames using large paperclips and soldering them together.  After trying this a few times is became very apparent to me this was the way to go, hence the birth of Switchy 1.5 and Head 2.0.  

   Head 2.0 uses actual IR sensors instead of the Photodiodes I had used in Head 1.0 and this time I free formed the whole circuit right on the motor instead of putting it on a prototype board.  These two changes made Head 2 much more responsive to changes in light levels and light movement, he will follow a light so well it almost freaks you out.  The last and biggest change is the solar panels on Head 2.  It came to me one day that no matter how cool these robots are changing batteries is a lot like changing diapers... It ain't no fun and it gets spendy quick.  So I ran two solar cells to a 5v regulator and powered Head 2 that way so he would automatically 'sleep' when it's dark.  I used a paper clip frame to help support the solar cells, you would be surprised how well the frame works, just be sure to use flux when attaching the clips even if your solder has flux in it otherwise it's almost impossible to get a good joint.