Gertrude (an LED_a_Awesome)
Gertrude uses two stepper motors to move an LED in a high resolution x/y plane. The movement of the LED is photographed using exposures usually between 30 and 90 seconds. Gertrude can either be programmed to "print" a design automatically ("Christopher & Daniil", the Hell Yup!: Scanlines shots) or controlled live via a joystick (Open&Close portrait series). The two stepper motors are driven by two h-bridges controlled by an Atmega8 and the tricolor LED is driven by one dual- and one single-channel digital potentiometer.
Here you can see Gertrude's polycarbonate frame and the wooden x-axis.

I usually leave traces of Gertrude visible in the shots I take. In this one I burned the x-axis bar into the top and bottom of the picture Gertrude's printing and I left part of the polycarbonate frame in the shot.

The LEDs I use now are tricolor red, green and blue. In theory, I could use it to "print" out any 8-bit color image fed to it from a computer. As it is set up now, Gertrude only needs the main Atmega8 controlling it and the accompanying h-bridges and digital potentiometers. The machine's independence from a computer is really important to me. I like for people to experience a double-take looking at the images--the viewer assumes the images were photoshopped but then there are small grains or details that give it a little something extra (like the glow given off by Daniil the cube). It seems incredible that the photographs document about a minute of lived time because the results are so vibrantly digital.
Enjoy!