# DIY 4-DOF 3D-printed robotic arm plays Nine Men's Morris

- Source: Reddit r/robotics
- Published: 2026-10-17T21:20:14.000Z
- RoboHot: https://robohot.news/en/items/dn6ytor0hm012dt6zgk8i63cm
- Original: https://www.reddit.com/r/robotics/comments/1x8lkji/diy_robot_arm_that_plays_nine_mens_morris/

## Summary

A 4-DOF 3D-printed DIY robotic arm has for the first time successfully recognized an opponent's moves via camera and autonomously completed a game of Nine Men's Morris. Joints J1-J3 use POM gears from Tarot 450 helicopter main gears paired with NEMA 14 stepper motors, J4 is driven by an RC servo, and the gripper is made of flexible TPU; the controller is a BTT SKR Pico 3D printer board with TMC2209 drivers supporting sensorless homing.