Reverse Engineering

2004 Dodge Running Board Trim

The customer had lost the passenger-side end cap off his running board. Months of searching turned up nothing — the part was discontinued years ago, no aftermarket replacement existed, and the only lead was the surviving driver-side trim still on the truck. He brought it in to see if it could be reverse engineered. It could.

The printed black end cap fitted to the front of the running board on a dark Dodge truck, photographed outdoors on gravel

Modeled From the Surviving Side

The remaining driver-side trim was measured and rebuilt in SolidWorks from scratch, with no factory drawings and no CAD file to work from. A PLA prototype surfaced dimensional errors and a design flaw baked into that first model — found on a test piece rather than after committing to a full-length run.

A series of cross-section test prints, worked from both ends of the part, verified full contour compliance before any material went into the complete part. When the customer questioned how PETG would flex in service, a cross-section sample was bent by hand right there to show him exactly how it behaves. After correcting the geometry, the full-length PETG part fit perfectly — a replacement for a piece that simply no longer exists.

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Slice It Right

This is a big part — 271.5 mm standing on end, a full overnight print. PETG is the material choice, not a preference: the cap lives outdoors on a vehicle, takes sun and road heat, and has to flex rather than crack when a boot catches it. Tree supports are genuinely required here at 48.40 g, about 18% of the filament, and come away from the curved underside cleanly.

Supports
Tree, Auto 30°
Material
PETG
Layer Height
0.12 mm
Infill
25% Gyroid
Nozzle
0.4 mm
Walls
3
Top / Bottom
5 / 5
Temperatures
250°C / 80°C
Bed Adhesion
5 mm Brim
Part Size
221.8×56.7×271.5mm
One Plate
263.28g · 21h 16m
Slice data: one part standing on end at 271.5 mm tall, 21 h 16 m and 263.28 g in PETG, with 48.40 g of that in tree supports

Built For One Truck

This was modeled to the passenger-side board on one specific 2004 Dodge, from that truck's own surviving driver-side trim. Running board styles varied by trim level and by whatever aftermarket boards a truck has picked up over twenty years, so check it against yours before committing to a twenty-one hour print — a cross-section test print off the end of the part is the cheap way to find out, and it is exactly how this one was verified.

Got a part that is discontinued with no replacement in sight? That is exactly the kind of problem I like to solve. Get in touch.

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Released under CC BY-NC-ND 4.0 — free for personal use, credit appreciated, no commercial use or derivatives.