Summary

Full 3D View

This model is inspired by the 1932 Ford Model B pickup truck.

The wheelbase of this model is about 1/8" shorter than the standard and may not be eligible for some races.

As with all of my builds, I'm not good enough at Fusion 360 to create a faithful replica, but I tried to capture most of the key elements.

What is a "pinewood derby car shell"?

A pinewood derby is an event created by the Boy Scouts many years ago. Each scout is given a pinewood derby kit typically consisting of a block of wood with slots for axles, 4 wheels, and 4 nails to be used as axles. The scout (and his dad, usually) will then carve the block of wood into the shape of a car, paint it and apply stickers, install the wheels on the axles, and then race it at the "derby", which involves a sloped track with a timekeeping apparatus.

An official scout derby will usually require that the parts in the kit be used for cars entered in the derby. Other organizations (including workplaces) often hold derbies, too, and some of them require the use of the parts in the box, including the block of wood.

These "pinewood derby car shells" are intended to be used with an official derby wood block, cut down to size, along with the axles and wheels included in the kit. A printable model of the shaped wood block is provided. You can either use the printed model or use it to accurately cut an official wood block down to size.

Notes:

• Body and bed: Supports are required. You can choose to print "Body.stl" and "Bed.stl" and add your own rafts, or you can print "Body with Minirafts" and "Bed with Minirafts" for a minimal raft-like surface that will aid in keeping the supports adhered to the build surface.
• Windshield and windows: I printed these using clear PETG. I printed the windshield using standard settings, flat on the print bed. The other windows I printed upright in vase mode, using the STL files with "minirafts" and supports. They could also just be printed flat and would probably look about the same. Black would also probably look good.
• Wheels: The wheels provided are for show only. They have "minirafts" included. Supports should be added between the miniraft and the wheel.
• Tires: For the show tires, I printed most of the tires using black, then paused the printer once it got to the last few layers and swapped the filament out for white.
• If you print the "Shaped Block.stl", print it upside-down. That will ensure that the axle slots print correctly.
• Everything else is pretty simple and straightforward to print, with minimal or no supports/rafts/brims.

Post-Printing

Smoothing

This car was smoothed with 3d printing resin and baby powder. You can find videos and guides online that describe the process, but here it is in a nutshell:

• Mix 1 part resin and 2-3 parts baby powder in an opaque container (so that it can be stored without hardening due to UV exposure).
• Using a paintbrush or cotton swab, spread a thin layer of the resin/baby powder mix over the body, wherever you want to smooth print lines and gaps.
• Use a UV flashlight (a cheap one--like the kind used to harden resin finger nail polish, which you can order from Amazon or buy in the pharmacy department of Walmart) to harden the resin.
• Sand the body smooth until there are no thick layers left.
• Repeat over any areas that are still rough.

This model is designed to drop on an official wood block carved in the shape of "Shaped Block.stl". The wheel slots are slightly closer together than on the standard block, though, so you'll need to cut a new wheel axle slot. Or just use the 3D printed block if your derby allows it.