Gee Wiz Derby horse racing

Gee Wiz Derby – A Retro Mechanical Racing Game

See it on Youtube: https://youtu.be/IRUvEnaOrFA?si=hQNzHT-qwubLgyCb

A remix of a classic 1920s randomized horse racing game, reimagined with modern 3D printing and basic electronics. No screens, no apps — just real-world motion powered by a simple DC motor and some clever design.

Highlights
– Fully 3D-printable in PETG
– Uses 7–8mm steel balls and a rotating roller to move the horses randomly
– Motor speed controlled via simple code, buttons, or a potentiometer
– Electronics are kept minimal: Arduino Nano, L298N, 10K potentiometer, and a few switches
– Optional: skip the Nano entirely and just use a DC motor controller

Build Tips
– A 12V power supply is recommended for best motor performance
– Use a little silicone lubricant or grease on the roller ends to improve spin
– Some light part wear-in may help horses glide smoother
– Make sure joins between track pieces are aligned and burr-free

Code
Includes three example sketches:

Hardcoded motor speed
Speed control via push buttons
Speed control via potentiometer

All designs are open source and remix-friendly. If you improve it, great! Share it forward.

Print Settings

• Printer brand:

  ELEGOO

• Printer:

  ELEGOO NEPTUNE 4 Pro

• Resolution:

  .20

• Notes:

  Print Settings Summary:
  Layer height: 0.2mm
  Wall count: 5 walls (0.4mm nozzle)
  Material: All parts printed in PETG
  Supports: Minimal, but required on most parts (modelled for easy removal)
  Orientation: All parts are pre-oriented for optimal printing
  Infill Recommendations:
  Most parts: 5–10% infill (sufficient for strength and material savings)
  Roller: 100% infill for solid strength and weight
  Horse bodies: 100% infill for smooth gliding and balance