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.
Printhead
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.

Boxes
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
Videos of this module in operation
Modules
Builds and revisions to this module.
Version 1

Pieces | Cost | Time |
---|---|---|
3000+ | $$$$ | 4 Months |
- The module uses an EV3 programmed using Python https://sites.google.com/site/ev3devpython/introduction.
- Had an overflow principle for caching.
- Handled 4 characters on screen.
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.