Braccio ROS2 Pencil/Pen Drawing Grip – Arduino UNO Q + Edge Impulse Demo

This project provides a custom-designed replacement gripper finger for the TinkerKit Braccio robot arm, allowing it to hold a pencil, pen or marker for robotic sketching, plotting and handwriting experiments.

I created the grip as an extension to my Arduino UNO Q Braccio project, which combines the Braccio arm with ROS 2, Edge Impulse, Gazebo simulation, camera vision and classifier-driven robot poses. The holder gives the demo a practical drawing end effector that can be used for motion-control tests, coordinate drawing, vision-guided marking and future Edge Impulse gesture, voice or camera-controlled sketching experiments.

Arduino UNO Q Braccio – ROS 2, Edge Impulse and Gazebo for simulation:

https://github.com/edgeimpulse/unoq-braccio

he original Braccio mounting interface is retained, including the 25 mm mounting-hole spacing. Instead of relying on continuous gripper-servo pressure, the pencil is held in a rigid split collar using an M3 screw and captive nut. This keeps the drawing tool fixed while the arm moves and makes it easier to reproduce sketches consistently.

Two ready-to-print versions are included:

8 mm version for common wooden pencils

10 mm version for thicker pens and markers

The included OpenSCAD source is fully parameterized and can be adjusted for tools approximately 6–12 mm in diameter.

Files to Print

Print one of the following:

braccio_pencil_grip_8mm.stl – standard pencil version

braccio_pencil_grip_10mm.stl – thicker pen or marker version

Required Hardware

1 × M3 socket-head screw, 16–20 mm long

1 × M3 hex nut

Original Braccio finger mounting screws

Pencil, pen or marker matching the selected holder size