Summary

This is a pinewood derby race car inspired by the 1997 Dallara F397 Formula 1 race car. It has been designed to run a standard pinewood derby race track (although I've never tested it), and includes holes that fit tungsten weights. With some effort, you can bring the weight up to the maximum 5 oz., and put most of the weight toward the back.

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:

Car body: On my 150mm x 150mm print bed, I have to print the car body diagonally. For best results, print on "Fine" settings (0.12mm level height in FlashPrint). Smaller level heights will produce a smoother surface. This body has a lot of very complex curves, so it takes a while to print--about 8 hours with the settings I chose. The part is designed to reduce the supports needed, but they are required.

All other parts are pretty straightforward...they print easily, and don't require supports.

A printable wood block is provided to use as a model to cut the official derby car kit wood block to the right shape.

By printing the "wood block" with 55% "line" infill, I was able to approximate the weight of actual wood.

Post-Printing

The parts all just superglue together. The body has guidance indentations to help ensure that everything fits together straight. The seat can just be aligned by sight (or omitted altogether).

You can add tungsten weights available on Amazon using the holes in the rear of the body. More weights can also be added on top of the wood block, if needed. Once you're satisfied with the weight, you can use any kind of tape to secure the plastic body to the wood block, and you're ready to race.

To get all the way up to 5 oz., you may need to drill additional holes in the wood block to add more tungsten weights. You could also print the parts with more infill, but printing lighter parts and adding more weight toward the back of the car will make it faster.

I've ordered some 1:24 scale sponsor stickers that I plan to apply to the car. I'll post more pics when I've done that.

How I Designed This

I had to use just about every trick in the book to make this work. The main body is a combination of a fairly complicated loft (between 4 profiles, with 4 rails) and a form that I tinkered with until it covered the wood block. (The actual shape of the body is too narrow, so this is a necessary adaptation.)

I'm pretty happy with how the front wing worked out. The real wing is very close to the ground, which wouldn't have worked on a pinewood derby track, so I had to improvise.