Device Details


It’s important to be able to catch the attention of a professor/teacher if you simply need to ask a question. Raising hand is a standard way of getting others attention around the world regardless of the environment and it’s globally used in classrooms. Unfortunately, it may not be possible for everyone to physically raise their hands and we need alternative visual device could help them.

This device would be beneficial for someone who has difficulty or is unable to raise their hand for an extended period of time.


The Serial-Hand-Raiser uses a RGB LED to send feedback by flashing colors according to the incoming requests through the USB connection. It uses web serial to communicate with host through a web app. This allows the users to send different colours actions to the device to and display visual feedback to other users.

The web app can be accessed through following web page:

Serial-Hand-Raiser App


Serial-Hand-Raiser can be used to provide visual feedback via a web browser installed in the host device. The following web browsers are compatible:


The Serial-Hand-Raiser costs approximately $14.

Build Instructions 

All the required assembly documentation, software, hardware are documented in the project GitHub repository. All the necessary electronics for this project are listed and can be purchased online via provided hyperlinks in the bill of materials (BOM) file.

Skills Required

  •  3D Printing Skills
  • Programming

Time Required

  • Total print time: 60 minutes
  • Assembly Time: 10 minutes


  •  3D Printer
  • Computer with USB port


  • 1x Adafruit QT Py – SAMD21 Link
  • 1x USB Cable – USB A to USB C – Link

3D Printing

All components can be printed with no support at 20% infill. There are 3 pieces to the enclosure:

  • 1x Bottom Plate
  • 1x Holder Plate
  • 1x Top plate – (Translucent filament)


The code for this device is licensed under the MIT license.

The Hand-Raiser 3D printed housing is licensed under the Creative Commons – Attribution – Non-Commercial – Share Alike license.