Long-exposure light painting is long-exposure photography combined with the use of lights to "paint" shapes in the final photograph.
LightPainter is a robot with an RGB LED, which can be used to do light painting.
LightPainter's chassis is made entirely out of aluminium from empty Mountain Dew cans and hot glue. The hinges are made from the cut-up plastic bags the servos came in.
Collecting empty cans was simple, and cutting up the aluminium into strips and forming them into beams was straightforward as well. These beams were glued to pieces of flexible plastic to form "ball joints".
The Arduino provides the brains of the outfit. A few passives and a lot of wire connects it to the three servos in delta configuration.
All electronics are mounted on a breadboard, which is housed inside an empty Mountain Dew can. The rest of the robot is mounted on top of that.
The plan was to solve the inverse kinematics for the RGB LED on the tip of the robot. However, this turned out more complicated than expected. The final robot uses only forward kinematics.
USB power was barely enough for powering everything . This caused sporadic issues when load spiked, such as when all the servos stall at the same time. After some debugging, this was resolved by adding an external power supply.