On April of 2015 I built Quatrebot, a 2-link revolute-revolute robotic manipulator that can draw figures on a paper. The whole project comprised forward and inverse kinematics, trajectory generation, simulation on MATLAB, and physical implementation of the robot.
Some videos of Quatrebot V1.0 are available at: https://www.youtube.com/playlist?list=PLGfxcKWDu8uGFYPF09zJygbODrJB9hLQl
Author: Yoshua Nava