CJ Petka | Engineering Portfolio

Steel Rail and Trolley Monitor Transport System

Curved monitor raised on its arm above a desk, mounted to the trolley on the wall rail

Autodesk Inventor model of the rail, trolley, and monitor mount — Inventor model

Black steel trolley plate with bolts and a center mount — Trolley face

Underside view of a trolley wheel riding inside the steel rail — Wheel in the rail

Goal

Carry a VESA-mounted monitor along a fixed 13 ft span.

What I did

Modeled the rail and adjustable trolley and produced technical drawings in Autodesk Inventor
MIG welded the steel structure across more than 100 welds
Turned custom trolley wheels on a lathe

Result

Installed and tested the finished system.

Type: Self-developed project
Date: Spring 2024
Steel span: 13 ft
MIG welds: 100+
Tools: Autodesk Inventor, MIG welding, lathe, steel fabrication

React to the Pressure

Yellow and black striped reactor-themed game with green, red, and orange buttons, a valve handle, and radiation symbols — Finished game

CAD renders of a cross-shaped valve handle and a three-blade handle — My handle designs (CAD)

Wiring inside the laser-cut enclosure, seen from the front — Wiring inside the enclosure

Goal

Build an engineering-failure carnival game for the Fall 2025 Expo. Ours is a Chernobyl-style control panel: shut off the blinking lights before the reactor melts down.

What I did

Laser cut the enclosure and drilled mounting holes for the inputs
Designed and 3D printed the valve and switch handles
Soldered and repaired wiring, then debugged the Python game code on the Pico

Result

Demonstrated the finished game to the public at Northeastern's Engineering Expo.

Type: Cornerstone of Engineering 1, team of 4
Date: Fall 2025
Player inputs: 6
Spent on materials: $7.50
Tools: Laser cutting, 3D printing, CAD, soldering, Raspberry Pi Pico, Python

Drone Package Delivery System

DJI Mini 2 hovering indoors with the release mechanism and landing legs mounted underneath

Raspberry Pi Pico electronics and wiring assembled on a desk — Electronics assembly

Radio module with a spring antenna on a breadboard — Radio module

DJI Mini 2 drone seen from above — DJI Mini 2

Goal

Drop a small package from a DJI Mini 2, which has no built-in payload release, without relying on the drone's own controller.

What I did

Designed a servo-actuated release mechanism and airframe mount sized to the drone's payload margin
Programmed paired Raspberry Pi Pico microcontrollers to trigger the release over shortwave radio

Result

Remotely airdropped a small wheel of cheese into a waiting hand as part of a promposal.

Type: Self-developed project
Date: Spring 2025
Tools: Raspberry Pi Pico (×2), MicroPython, servo actuation, radio link, CAD

Spring-Powered Competition Vehicle

Black 3D printed spring-powered vehicle with large spoked wheels on a classroom table

Slicer preview of a 3D printed drive gear — Sliced drive gear

CAD model of the vehicle frame and gear train — CAD model

Goal

Build a spring-powered vehicle that travels as far as possible.

What I did

Modeled and 3D printed the vehicle with a 1:144 compound gear reduction
Tuned printed gear tolerances so the gear train meshed reliably at high reduction

Result

Set the school distance record at 76 m.

Type: Engineering competition
Date: Fall 2023
School record: 76 m
Gear reduction: 1:144
Tools: CAD modeling, 3D printing, gear train design