Aaron Gilbert

The goal

A deeper, more aggressive freight-train sound from real locomotive hardware, instead of the horn’s brighter stock tone, plus a way to fit five bells, a tank and two compressors on a compact pickup.

The hard part

Making the 1L bell, a long bell that plays the lowest note. I swapped it in for the horn’s smallest, highest-pitched bell. Beyond reference photos, I couldn’t find the bell’s internal shape, so I worked out its flare in Fusion 360, using AI to help with the research, and revised it before 3D-printing the whole bell in PETG plastic. It has been tested at 175 psi without cracking. Then I printed inserts for two more bells, the 3A and 4A, to push the sound closer to a K5HL.

Air and mounting

I upgraded the solenoid (the electric valve that releases air into the horn) and the plumbing, bolted the air system into the bed, and built a heavy-duty cage from strut channel, angle and rebar. The cage bolts together and sits on bushings that isolate it from the frame. The air system usually runs at 150 psi, has been tested at 175, and also supplies my semi-truck horns.

Wiring

The horns are only part of what I’ve added to the truck, so I rewired it to match. Under the hood, I designed and 3D-printed boxes for relays, fuses and wire connectors. In the bed, a larger printed box collects the added circuits, which run through a 1-inch wire loom to the switch panels up front.

How it turned out

To my ear, the printed 1L made the biggest difference, giving the horn a deeper, more aggressive sound.

The challenge

That season’s game, INTO THE DEEP, had robots pick up game pieces called samples and score them in baskets, or hang clipped samples (specimens) on a raised bar. Each match starts with 30 seconds where the robot runs on its own, then two minutes of driver control, and robots can climb at the end for extra points.

Starting over

Our first robot took about three months to build. It was mostly acrylic and used one large arm to do everything, which made it slow and limited its reach. We scrapped it, started from scratch, and built the replacement in a little over a month.

The new design

The big change was splitting the work between two smaller arms: a horizontal mechanism picks up a game piece and passes it to a vertical lift that scores it high. The robot drives on mecanum wheels, so it can move in any direction. Odometry wheels underneath track its position, which lets it correct its course if another robot bumps it. At the end of a match, it can also climb, lifting itself off the floor.

Team results

Our team won the Innovate Award at the San Diego Turing League Tournament in February 2025, and ranked 13th of 36 in qualification at the San Diego Championship in March.

The competition

NASA Student Launch is a year-long rocketry challenge run by NASA. Teams design, build and fly a rocket that carries a payload, document the design along the way, and launch in the spring.

My part

I modeled parts and assemblies in CAD, turned them into dimensioned drawings the team could build from, and drew the electrical schematics and wiring diagrams that show how the electronics connect. My CAD work included the payload bay for a camera designed to rotate after landing and take panoramic photos; the payload worked most of the time. I also documented how the design developed.

How it turned out

We flew the rocket at the April 2023 launch. Our team placed third for Altitude, third for Judges’ Choice and second for STEM Engagement in the middle/high school division of NASA’s 2023 Student Launch.

How it came together

1. Built a plywood mockup to settle the size and proportions
2. Moved the dimensions into Fusion 360 and refined the design
3. Laser-cut the metal parts
4. Welded and assembled the frame
5. Wired the electric drive

What I’m proudest of

How fast it came together: the main design and build took about a week, from plywood mockup to a rigid metal frame.

How it works

Eight garage-door extension springs power the throw. A winch pulls the beam down against them, and a quick release lets it go. The counterweight is adjustable: I can add weight or move it forward and back, and different attachment points change the spring tension.

What it’s made of

A 2×4 frame braced with quarter-inch plywood, plus custom 3D-printed parts: casters, shaft sleeves and counterweight brackets.

The hard part

Not the rocket, the paint. The first coat was black; then I masked the triangle shapes and layered red, dark gray and light gray, masking on top of masking. Each layer hid earlier work, so the challenge was planning how much of each color would still show at the end.

How it turned out

The four colors cover roughly equal areas and work well together, which is what I was aiming for. Its one flight went well, and it came down under its parachute.

What the switches control

• The rear air tank: fill and release
• The truck’s second electrical system
• The horns: one switch picks the stock horn or the added horns, and three more choose which of them sound
• Interior lights, bed-shell lights, rock lights and fog lights
• The light bar
• One spare switch for whatever I add next

Separately, I installed and wired a store-bought PA system in the truck.

Why printed

The original trim stays untouched. When the setup changes, I edit the model and reprint a panel instead of cutting into the truck. It’s one of my favorite truck projects.

How it adjusts

Each support pivots on all three axes, so the suction cups follow the curve of the roof. That adjustability was intentional: I wanted a mount I could also set up on other vehicles or use with other lights, not one made for a single roof.

The hard part

Getting the hinges and printed connections right, so four flat suction cups could sit on the curved roof instead of being forced onto one plane. There’s only just enough room on the roof for all four cups.

Shock-absorbing parts

Everything purple is 3D-printed in TPU, a flexible, rubber-like plastic. It works like a grommet, soaking up road shock so the horns don’t get beaten up while I drive.

Air supply

They started on a small 2-gallon tank and compressor. When I built my train-horn system, I upgraded to an 8-gallon tank with dual compressors, and now both horn sets run from it.

How it turned out

Both sets are still on the truck, and I can sound either one on its own or both together. To my ear, the combination is deep and unusual, and it echoes and carries a long way.

What I did

I opened up the adapter, soldered and wired USB connections for phone charging, then designed and printed a housing for the board and new buttons for its controls.

How it went together

I modeled the box and its openings in Fusion 360, built an inner wooden frame, added plywood panels, then carpeted the outside. Last, I modeled the driver grilles and printed them in black.

How it turned out

Looks were the main goal, and that’s what I’m happiest with. To my ear, it sounds great too.

The X-Maxx

Two fans push air over the speed controller (ESC) and brushless motor. A 3D-printed roll cage helps protect the body during rollovers, and weak spots got printed parts or aluminum replacements, including all-aluminum steering. For lighting, it has headlights, rock lights, two light bars (one on the roof, one up front) and a lot of rear lights.

The Slash wheels

I designed rims and tires for the Slash in Fusion 360 and 3D-printed them.