Kosti-1 is a 5 DOF open-source robotic arm with a maximum payload of 500gm, a reach of approximately 55cm and a total part cost of around $700; the arm lies in the mid-range between small servo arms and multi thousand dollar projects and is generally aimed towards educational and hobby purposes.
Assembly files can be found in sldprt.zip
Design process and manual can be found in:
https://www.reddit.com/r/robotics/comments/15dx5fs/releasing_kosti1_how_to_design_your_own_robot_arm/https://www.thingiverse.com/thing:6147832