Control webcam lens with standard servo would be fun.See the video - http://youtu.be/27uGegRznfE.Next thing? Autofocusing the webcam, of course!Note The lens_gear in model files has 14mm diameter which is the outside diameter of the webcam lens. But I modified the lens_gear hole slightly bigger than the webcam lens and taping servral time the lens to make them holding tight. This would be a safer way not to break the webcam board and lens while attaching the lens_gear. But if you want, you can leave the lens_gear hole tight and trying to press it onto the lens by your vice or other tools. ;)Now, you need a servo controller. If you're an Arduino fan just like me, check to see http://arduino.cc/en/Tutorial/Knob.Modeling your gears in BlenderIn my case, center distance is 26mm. Servo horn diameter is 24mm. Lens diameter is 14mm. I've tried two gear ratio designs. 1:1 gears and 1:1.5 gears. And my final choice is 1:1.5 gear ratio. If you have longer center distrance you are so lucky. Servos are limited in rotation angles, you know. More gearing ratio will increase the focal length ranges.Blender 3D gear parameters ==servo gear == Number of teeth: 15 Radius: 15.0 Width: 2.0 Base: 1.5 Dedendum: 1.0 Addendum: 2.0 Pressure Angle: 20.0 others: 0.0 == lens gear == Number of teeth: 10 Radius: 10.0 Width: 3.0 others: same above.And to make them solid, I did followings. FYI, see http://www.katsbits.com/tutorials/blender/learning-modeling-mesh-editing.php first if you are not familliar to the Blender 3D. == Lens gear ==== Servo gear ==Congratulations! Now, you've got two solid gears.