Korean design firm Everyware has made a robotic arm  from wood that is computer programmable to create beautiful 3D light paintings. Below is the company's intro about this impressive tiny robot:

Marcel Duchamp(1887~1968)’s first work to provoke significant controversy was Nude Descending a Staircase, No. 2 (1912). The painting depicts the mechanistic motion of a nude, with superimposed facets, similar to motion pictures. In a single frame, it shows elements of both the fragmentation and synthesis of the Cubists, and the movement and dynamism of the Futurists.
Luxo is a robot invented to draw a superimposed light painting. Inspired by the Ducamp’s painting, Luxo depicts dynamism of a luminous particle in a 3 dimensional space. Using a small LED bulb mounted at the tip of a custom-made 4 degrees of freedom robot arm, Luxo can freely move its light source in a space drawing hallucinating light streaks by long-exposure photography. Scattered on its surroundings, the light dancing in the space creates a painting that attracts you to the imaginary void where time is melt along with dynamism of the Luxo itself.

System :

A true-color LED mounted at the tip of a 4-DOF(Degrees of Freedom) wooden robot arm moves in a pre-calculated path. Using a bulb-shot photography, the robot creates a various sets of light paintings. All the photos were designed and simulated before taking a real one through a end-effector path calculator software of the robot arm.
 

(all photos courtesy of Everyware)