My all-time favorite toy from childhood was the Hot Wheels Shark Cruiser. I absolutely loved Hot Wheels cars as a child. Even now, as an adult, I will pick up one or two Hot Wheel cars when I visit the grocery store. As a fun 3D printing challenge I wanted to see how small I could make a toy car with rolling axels and wheels. After many iterations, I came up with a simple snap-together micro car kit. In this Instructable, I will show you how to put together my 3D Printed Micro Car Kit and how you can use my template to design your own. I have two designs you can choose from:

Simple Racer

-or-

Simple Tune

Alright, let's grab some plastic nippers, fire up a printer, and start making!

Supplies

Parts

PLA or ABS filament of your choice.
Your choice of a car kit:
- Micro Car Simple Racer download for free here: https://www.tinkercad.com/things/hpjoQGgpQh5
- Micro Car Simple Tune download for free here: https://www.tinkercad.com/things/7EAUUn4QNcw

Tools

3D Printer
Your favorite slicer, I use Cura
Pencil
800 Grit Sand Paper
Plastic Nippers

Optional

Micro Car Template download for free here: https://www.tinkercad.com/things/gdQnl5Ql9oW

Step 1: Print a Kit!

If you don't have a 3D printer see the notes section below.

Once you've chosen and downloaded a kit load it into your favorite slicer. I use Cura for my Ender 3 printer. The following are the settings I suggest using to print the kit:

Infill Density 20.0
Infill Pattern Tri-Hexigonal
Printing Temperature 195 - 200 C
Build Plate Temperature 50
Print Speed 50mm per second
Supports On
Support Overhang Angle 30 degrees
Skirt On

Once you are satisfied with the settings slice and run it on your 3D printer.

Note: If you do not have access to a 3D printer check your local Library, Makerspace, or University. Many public libraries in the United States have free or affordable printing services. My public library offers free 2hr PLA prints to the community. There are also online printing services available too. For example, Shapeways.

Step 2: Snap It Together!

Once your print is complete carefully remove it from the plate. Using plastic nippers remove supports. Lightly sand the axels and axel housings. Use a pencil to coat the axels and axel housings, this will allow them to spin smoothly. Place the lower body face up. Place each wheel and axel set into the axel housings. Carefully, attach the top chassis to the lower one. Pick the car up and push the chassis together until you hear a snapping sound.

Notes:

If the wheels on your car aren't completely round lightly run it up and down on sandpaper. This will round the wheels after a dozen or so passes. Only do this procedure if the wheels rotate when pushed!
If your wheels and axels do not rotate take apart the car and sand down the axels and axel housings again.

Step 3: Ready! Set! Race!

The 3D Printed Micro Cars work well on cardboard ramps and the orange Hot Wheels track. Use some blocks or books to set up a ramp to have a fun race!

Step 4: Make Your Own Design!

You can find a template of my 3D Printed Micro Car kit to make your own designs here:

If you use Tinkercad use the Remix option otherwise feel free to download and edit in your favorite CAD program.

In Tinkercad, I use basic shapes to make a front end, bonnet, and rear spoiler. Once you have an object you wish to attach to the template roughly move them in place to get an idea of what your car will look like. When attaching an object make sure to not overlap the front and back of the chassis. To accomplish this in Tinkercad use the Ruler and Align tools. When attaching a bonnet make sure not to sink it into the hole on the top chassis. If the top chassis hole is filled the car will not snap together. Once everything is centered and placed move the wheel and axel objects into the axel housings to make sure they won't rub against the objects you added. When you are happy with the car group your designs to the top chassis. Organize the parts in the orientation you would like them to print in. I had the best luck with printing the wheel and axel objects by raising them 1mm off the print bed. When all is set group all the objects together, download, and print!

If you have any questions please comment and I will reply ASAP. Also, I would love to see your 3D Printed Micro Car designs! Post a pic if you like. Happy Making :)