Peg Lab Plinko! — Ethan Lazar

Overview

The brief: design a STEM learning toy that 4th and 5th graders would actually want to play with, and that could teach something along the way. Our team landed on Peg Lab Plinko! — a Plinko-style board where the peg layout and lighting respond to player input, turning the classic dropped-puck mechanic into a small physics lesson. Two teams take turns placing pegs to build strategic routes, then launch balls with spring-loaded launchers trying to land in LED-lit target wells. The electronics — a SparkFun RedBoard, photoresistors, and color-coded LEDs — automate scoring and randomize targets each round. The toy came in at $47.08 (well under the $100 budget), survived two live showcases with only two pegs breaking, and the classroom teacher asked to keep it.

Students playing Peg Lab Plinko! at the final showcase — **Gameplay**Students playing at the final showcase

Top-down detail of the Plinko board showing peg grid, wells, and LEDs — **Board detail**Peg grid, wells, and LED targets

What I did

Co-led a 4-person team through concept, prototyping, and final build over the semester.
Designed and wired the full electrical system — LEDs, photoresistors, slide switch, and SparkFun RedBoard — handling all soldering and breadboard layout.
Wrote the Arduino C++ code using the TaskScheduler library to monitor all six photoresistors concurrently and automate light switching for gameplay.
Created the final CAD assemblies in SolidWorks, gathering individual part files from teammates and producing exploded views and engineering drawings.
Delivered monthly design reviews and incorporated peer and mentor feedback into successive iterations of the toy.

Breadboard and SparkFun RedBoard wiring under the Plinko board — **Electrical**Breadboard + RedBoard wiring

SolidWorks exploded view of the Peg Lab Plinko! assembly — **CAD**SolidWorks exploded view

Design process

The project moved through five milestones over the semester — from problem framing and cardboard prototyping to a fully functional, painted, and wired final product. Each milestone ended with a design review where the team presented progress and incorporated feedback.

M2 cardboard prototype of the Plinko board — **M2 · Cardboard**Concept prototype

M3 first laser-cut wood build — **M3 · First build**Laser-cut wood

MCCS students testing the prototype — **M4 · User test**MCCS classroom visit

Final painted Peg Lab Plinko! board — **M4 · Final**Painted + wired

Cardboard concept → first laser-cut build → user testing with MCCS students → final painted product.

Component details

Engineering drawings of the six peg varieties — ramps, splitters, cylinders, hopper — **Peg varieties**The six interchangeable peg types players choose from

**Launcher drawing**Engineering drawing of the spring launcher parts

Exploded view of the spring launcher — sleeve, plunger, and spring base — **Exploded view**Sleeve, plunger, and spring base

Assembled spring launcher ready to fire — **Assembled**The main physical interaction point

What I learned

Designing for kids forces clarity. If a 4th grader can't figure out what to do in the first ten seconds, the engineering doesn't matter. Most of the late-stage iteration was about removing friction from the play experience, not adding more features — for example, we found that accidental light changes from fingers hovering over photoresistors disrupted gameplay, which taught me how much sensor placement and threshold tuning matter in a real user environment.

On the team side, this was my first real exposure to running monthly design reviews — preparing the work, taking critique, deciding what to act on, and moving forward. That cadence has carried over into how I work in AerospaceNU now. I also learned the full weight of documentation: maintaining the design notebook wasn't just busywork, it was how we communicated progress across milestones and justified decisions to reviewers.

Wide shot of the final showcase — students crowded around the Peg Lab Plinko! station — **Showcase**Students didn't want to leave the station — the teacher asked to keep the toy for the classroom.