If you’re tired of the model car kits available in stores, why not design your own? Designing your own model car can be an exhilarating project that gives you control over the details of each piece, such as size, shape, and color. Designing toys is also a great way to get older kids excited about science and engineering. (Note: Final product not intended for use by children)

If you’re a teacher, conceiving and designing a model car are great exercises in design thinking for students, particularly for the stages of ideation and prototype design. You can find a quick video on the stages of design thinking below. You can also find a complete lesson plan devoted to this topic, as well as instructional materials such as learning objectives, test materials, and evaluation rubrics here. While the focus of this project is mostly on the “how-to” of design, you can find a series of videos on using Sketchbook Pro to work out ideas before you design here.

Step 1: Download Autodesk 123D Design

Before you start, download and install Autodesk 123D Design (it’s totally free). 123D Design makes it easy to manipulate all kinds of shapes and create viable designs using numerous materials. For a general tour of the interface and commands, see these short tutorials:

Step 2: Create the Car Profile Sketches

First, Use Primitives > Box to create a 65mm height x 200mm length x 100mm width cube. Think of this box as you might a plain block of wood if you were carving this car model. Use Sketch > Project to select the end face, and then Use sketch>polyline and sketch>spline to create one half of the profile. You can easily modify the sketch by adjusting the location of any of the points.

After you have drawn a vertical line between the midpoints to close off the profile, select the sketch, and then select Mirror. Mirror the sketch about the vertical center line to create the end profile of your car.

Using the same workflow, create the sketch profile for the side of the car, the only difference being you will sketch the whole silhouette rather than mirror half of it. For a step-by-step video tutorial on this stage, see below.

Step 3: Model the Car Body

First, hide the solid box. Select the end profile, and Extrude them the full length of the car (200mm in this example).

Next, extrude the side profile the full width of the car (100mm for this example). Be sure to use the Intersect option to create a the car body at the intersection of the two extrusions.

Give your car some personality by Applying material. Select all surfaces, choose a material, and apply. Be sure to use Modify > Fillet to smooth whatever sharp edges might remain on the car. For a step-by-step video tutorial on this stage, see below.

Step 4: Model the Wheel Openings and Scale Wheels

Show the sketches if you hid them in the last step. Use Sketch > Circle to place a circle at the rear of the car, approximately where the rear wheel will go (in this example, we use a 16mm radius). Use sketch>polyline to add 2 lines, making the wheel well flare out.

Next, use Sketch > Trim to remove extra lines, and extrude the profile the width of the wheel well (a cut of 20mm in this example). Use Modify > Fillet to round the edges around the wheel opening. Repeat this process for each wheel well. Save your car body.

Lastly, open a new file. Under Kits > Motorcycle > Components, select a wheel. Save the wheel To My Computer as name_wheel. Use the Measure tool to measure the radius of the wheel. Scale the wheel to a radius that will fit in your wheel well (15mm for this example). Apply black paint material to 3 faces on the outside of the wheel to create tires. Save the file. For a step-by-step video tutorial on this stage, see below.

Step 5: Add the Wheels

Insert your wheel file into your car body file. Use the Move tool to put the wheel more or less into place, and rotate it so that it is in line with the car. Continue to drag it closer until it is in the wheel well you created. Use Grouping, select the car body, and select the wheel to group the two parts together.

Repeat this process with each of the remaining wheels, making sure that they are level with each other and ultimately grouped. For a step-by-step video tutorial on this stage, see below.

Step 6: Print!

In order to print parts from 123D on your MakerBot you will need to install the Autodesk 3D Print Utility which will prepare your parts for printing. For more information on the Autodesk 3D Print Utility click here.

You will also need to download and install the latest version of the Makerware™ software from MakerBot. The software is free of charge and can be downloaded here.

Once a part has been created and is ready for printing you can select 3D Print option from the 123D Menu. This will bring up the 3D printer dialog where you can select your printer and options for printing.

After setting up your printer options, you will be given the choice to save as a .stl file or send directly to the Makerware software for printing.

If your printer is not listed in the Autodesk 3D Print Utility, you can still export to a .stl file directly. This will allow you to use any software your printer requires. This can be done by selecting the Export STL option from the 123D Design menu.

Lastly, if you don’t have a 3D printer, places like TechShop have the tools to turn your design files into physical objects, and staff the people who can show you how. Places like Shapeways can even print them for you.