1957 Lotus Seven (Pinewood Derby Car Shell)

Summary

Full 3D View

The Lotus Seven was produced by the British car manufacturer Lotus between 1957 and 1972. It is a simple, lightweight open top two-seater. Early engines didn't have much horsepower, but the car has always been quick and sporty because of its weight.

What is a "pinewood derby car shell"?

The 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.

Print Settings

Notes:

• Car body: Extensive supports are required. In Bambu Studio, I use Normal (auto) supports in Snug style. I prefer ABS for my car bodies because it sands smoother than PLA, even after using the smoothing technique described below. But PLA will work.
• The wheels, front fenders and exhaust also require some supports.
• Steering wheel, rear fenders: Outer brim suggested.
• All other parts print really easily.

Post-Printing

Just super glue all the parts together.

“Show wheels and tires” are included, but are optional. They are not suitable for racing--you should use the wheels that come with the kit if you race the car.

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.

Weights

You can add tungsten weights to the holes in the rear of the body. If you plan well, and use enough infill, you can maximize the weights and end up right at 5 oz.

Patreon/Commercial License

I just do this for fun BUT if you insist on throwing a couple of bucks my way or if you'd like to sell prints of any of my designs, see my Patreon page.