Lego GBC Scrolling Display was my first module built, it had its origin in watching a bunch of GBC YouTube videos and wanting to come up with a mechanism that was both original and provide a technical challenge.

It took 4 months of experimenting to come up with a working design that I considered show ready.

Early prototype

It took 4 months of experimenting to come up with a working design that I considered show ready.

This video is about 2 months into the build where the design forced balls onto the the pin belt.


The print-head forms the core mechanism of the printer.

It uses 4 EV3 motors to operate 5 dot pins and the dropping mechanism.

  • Motor 1 is for dots 1 and 2.
  • Motor 2 is for dot 3.
  • Motor 3 is for dots 4 and 5.
  • Motor 4 is for the drop and load.

Each letter of the Alphabet is encoded in a dictionary that represents them as dots, for instance, A = (11110,00101,11110) or L = (11111,10000,10000) in this way the program knows how to drive the motors to print a letter.

Night Lighting

Lego GBC Scrolling Display looks great at night and the words can be easier to read.

It uses some of my custom Lego UV/Led lights to light up the start reservoir and balls path.

The EV3 is also lit up so the program running is visible.


Lego GBC Scrolling Display packs into a single 24x18x10″/60x46x25cm  bespoke cardboard box.

In order to fit, it breaks into several key pieces.

  • Print-head.
  • Conveyer belt, this actually splits in the middle and is compressed together.
  • EV3 Brick.
  • Print-head feed conveyor.
  • Input Lift module.
  • Various ramps and cables are packed in a top box.

You can read about other boxes here Boxes for Lego GBC Modules.


Videos of this module in operation


My Scrolling Display module won a “Staff Favourite Award” at BrickFair NJ 2017.


Builds and revisions to this module.

Version 1

Pieces Cost Time
3000+ $$$$ 4 Months

Version 2

Pieces Cost Time
3000+ $$$$ 2 Months

Entirely Re-engineered with the exception of the print head.

  • Longer belt to show full LEGO GBC.
  • More reliable input and recirculation sections.
  • Taller to allow easier clearing of lost balls.
  • Made ev3 visible so people could watch program.

Version 2.1

Pieces Cost Time
3000+ $$$$ 2 Weeks
  • Added an NXT to automatically cache balls.
  • Changed the belt liftarms to black.