Tactile Protractor

Description of the model

Tactile Protractor

In dutch we called this the Brabo, short for Braille boog (arch). This tool allows students to measure and draw angles in a very easy way. There have been various forms of this model in production in the past but they didn’t meet the needs of teachers in the Netherlands, stopped production or had very high costs. That is why we made it into an easy 3D printable model.

The model has two components

The arch
This has all the information about the angle. Each 5 degree step is made tactile and for 10 and 45 degrees additional symbols are added. This way a user can feel the height of the angle.

The base and arm
The arm allows the user to align the bottom and top half with the angle that is be measured, either on a real life object or tactile drawing. After aligning the arm with the angle, you put the base back in the arch and you can read out the angle.

You can also do this the other way around to draw a certain angle. Set the base and arm in the arch according to the angle you need. Take out the base and arm and draw the angle on a piece of paper.

This model was designed and tested as part of the 3D4VIP project.

Printing instructions and tips

The model should be printed on 0,2 or 0.1 layer height. Two colours is preferred as it helps the user set the base and arm in the arch in the correct way. You can add the colour switch after 2.2 mm to have a fully yellow small arm with a black tip.

You can fit 4 of them on a regular sized printer.

You need an M2 bolt and nut.



Loading file
  • Fullscreen
  • Wireframe
  • Zoom In
  • Zoom Out
  • Rotation
  • Screenshot
  • Help


  • Rotate with the left mouse button.
  • Zoom with the scroll button.
  • Adjust camera position with the right mouse button.
  • Double-click to enter the fullscreen mode.
  • On mobile devices swipe to rotate.
  • On mobile devices pinch two fingers together or apart to adjust zoom.
  • On mobile devices 3 finger horizontal swipe performs panning.

Additional Models

  • Brede-Arm-V2.stl
  • Boog-V2.stl
  • Dikke-arm-V2.stl