Tinkercad Tutorial: Build a Simple 3D Printable Colorimeter for STEM Laboratory Learning (2026 Version)

Designing custom scientific equipment may seem intimidating, but with modern, beginner-friendly CAD software such as Tinkercad, educators can create meaningful STEM laboratory projects without prior engineering experience. This tutorial walks you through the step-by-step process of designing a simple 3D-printable colorimeter that can be fabricated on nearly any commonly available FFF (Fused Filament Fabrication) 3D printer and used as the foundation for an engaging, hands-on laboratory activity.

Tinkercad, a free, web-based 3D design platform developed by Autodesk, is one of the most approachable computer-aided design (CAD) programs available for educators and students. Its intuitive drag-and-drop interface allows beginners to create functional 3D models using simple geometric shapes, eliminating the steep learning curve often associated with professional CAD software. Because it runs entirely within a web browser, requires no installation, and is compatible with Windows, macOS, Chromebooks, and tablets, Tinkercad is easily adopted in K–12 schools, colleges, makerspaces, and outreach programs. These features make it an ideal introduction to 3D design while providing a powerful platform for creating customized laboratory equipment, engineering prototypes, and other STEM teaching resources.

Rather than simply providing downloadable design files, this tutorial emphasizes the design process itself. By building the colorimeter in Tinkercad, educators gain the skills and confidence to understand, modify, and customize the instrument to meet their own instructional goals. The design intentionally prioritizes simplicity, using straightforward geometric shapes and beginner-level modeling techniques that make it suitable even for first-time CAD users.

The completed colorimeter is designed for educational use and can be assembled with inexpensive, readily available electronic components using alligator clip–terminated lead wires, eliminating the need for soldering or a solderless breadboard. This low-barrier approach makes the project accessible to a wide range of classrooms while helping students move beyond treating scientific instruments as mysterious "black boxes." Instead, students can build, explore, and understand how optical, electronic, and analytical components work together to measure light absorbance.

Whether incorporated into chemistry, biology, environmental science, physics, or engineering courses, this simple colorimeter provides an affordable platform for authentic STEM laboratory investigations, including food dye analysis, water quality testing, reaction kinetics, Beer–Lambert law experiments, and many other absorbance-based activities. By the end of this tutorial, educators will have both a functional laboratory instrument and the knowledge needed to adapt its design for future classroom innovations.

Only access to Tinkercad is required for this tutorial.

The digital design can be produced using a 3D printer. Instructions for wiring and using the colorimeter are included in my previous colorimeter Instructables projects.

Sign in or create a Tinkercad account by visiting www.tinkercad.com. Accounts are free and this online CAD software is one of the most intuitive programs available for new users. I often think of it as a 3D version of working with shapes in Microsoft PowerPoint. Once you have developed confidence with Tinkercad, you may wish to explore more sophisticated CAD software packages, such as Autodesk Fusion, etc.

Once you are logged in to the site, click on the blue “+ Create” button on the top-right side of the screen. Select “3D Design” and you will be greeted with a blank workspace, known as the Workplane. You may adjust the grid layout by clicking the “Settings” button in the lower right-hand corner of the screen. For now, leave the Workplane with the default settings. Notice the toolbar alongside the right of the screen. It contains a variety of useful menu options and functions. First, left-click on the “Ruler” icon from the menu and drag the ruler onto the lower-left corner of the Workplane. This ruler option will allow you to see the exact dimensions of the items to be used and provides a way to enter in precise measurements to customize the shapes used in this tutorial.

Left-click on the “Box” shape and drag it to the center of the Workplane. Once the red box is on the Workplane, you can begin to appreciate the intuitive nature of Tinkercad. At this point, you may adjust the box's size in all three dimensions by clicking an axis and dragging it to the desired length. You can also accomplish this by clicking one of the values and manually typing the desired value into the measurement you wish to alter. You can translate the Workplane box by left-clicking and dragging it along the x- and y-axes (the Workplane is designated as the xy plane in this software). You may also translate the box along the z-axis by clicking the black arrowhead above the box and sliding it up or down on the Workplane.

This colorimeter requires a sample holder. Start forming the cuvette holder from the box currently on the Workplane. Using one of the methods described above in step (3), alter the dimensions of the box so that it is now 18.0 mm wide, 18.0 long, and 40.0 mm tall. You may adjust the “camera angle” or view of the Workplane by holding down the right mouse button and moving the mouse around. The view is always centered on the middle of the Workplane. Zooming in and out is done with the scroll wheel on your mouse. Don’t panic if the dimensions of your box disappear. You may bring them back by left-clicking on the box.

Now, begin to prepare the cavity that will house the standard 1.0 cm path length plastic or glass cuvette. Drag a new box onto the Workplane and set it to 13.2 mm wide, 13.2 long, and 45.0 mm tall. Lift this new box to a distance of 3.0 mm above the Workplane by translating the box upwards along the z-axis by left-clicking on the black arrowhead above the box and sliding it up.

Next, align the two boxes using the “Align” function. First, select both boxes by holding down the left mouse button and dragging the selection box to overlap both boxes before releasing the button. Alternatively, you could left-click one box and the other while holding down the shift key. Access the “Align” tool by left-clicking the menu icon at the top right of the screen. Align the two boxes by clicking on the center alignment dots along both the x- and y-axes. These are highlighted in the image at right.

Once the boxes are aligned as shown below, dismiss the align tool by left-clicking somewhere on a blank portion of the Workplane. The next step will instruct you on how to prepare a void, or cavity, but using “Hole” shapes.

“Hole” shapes are powerful tools used in Tinkercad. Select the second box, now centered and slightly above the first box, by left-clicking on it. Next, convert this box into a box-shaped “Hole” by left-clicking the “Hole” option in the “Shape” window. The selected box should change from red to transparent, as shown below. The hollow shape maintains the dimensions you assigned, but will result in a void when we group the objects later in the design process.

In order to give our sample holder some stability and prevent it from falling over during use, we will create a simple base. Drag a new “Cylinder” onto the Workplane and set it to 70.0 mm wide, 70.0 long, and 2.5 mm tall. Use the “Align” tool once again to center this new cylinder with the box along both the x- and y-axes. The result should match the design below.

Drag a new box onto the Workplane and set it to 15.0 mm wide, 50.0 long, and 25.0 mm tall. This new box will house our light path for the LED source and phototransistor detector.

Select all four of the objects on the Workplane and use the “Align” tool to center them all along both the x- and y-axes. Your design should look like the one shown below. This simple colorimeter is taking shape. Only a few more steps are required to complete the design.

Drag a new cylinder onto the Workplane and set it to 10.0 mm wide, 10.0 long, and 60.0 mm tall.

This cylinder will form our light path cavity. Convert this cylinder into a cylindrical-shaped “Hole” by left-clicking the “Hole” option in the Shape window, as used previously. The selected cylinder should change from orange to transparent. In order to align the light path, we will need to rotate the cylinder by 90 degrees. This is accomplished by left-clicking on the correct rotational arrow, as indicated below. Hold down the left mouse button and slide the mouse to the right to begin the rotation. Stop at 90° so that your shape looks like the one shown below. If things begin to get a little crowded on your Workplane, feel free to move objects by selecting them and dragging while holding down the left mouse button.

In the previous step, you may have noticed that the light path cylinder was too far above the Workplane to be useful in our design. It needs to be lowered from the current 25.0 mm distance to 13.0 mm, as shown below. Lower the hole cylinder along the z-axis by left-clicking on the black arrowhead above the cylinder and dragging it down. Alternatively, you may simply enter the desired value in the distance parameter shown below.

Select all five of the objects on the Workplane and use the “Align” tool to center them all along both the x- and y-axes. Your design should look like the one shown below.

This final step is important. Select all five shapes by using simultaneous pressing of “Ctrl” and “A”. Now use the “Union Group” tool to merge them into a single object. Notice how the hole shapes were subtracted from the other shapes to form voids.

Congratulations! You have completed your simple colorimeter CAD design! Now that you are becoming more familiar with Tinkercad, you may wish to refine your design using the skills explored in the previous steps.

Finally, in order to prepare your CAD model for 3D printing, it must be exported from Tinkercad. Simply left-click on the “Export” tab located at the upper-right corner of the screen.

Select “Download” and choose “.STL” as your model export choice for file format. STL files are the most common format for 3D printing.

The photos above show the (a) 3D printed colorimeter using the design produced from this tutorial. Once assembled, this simple colorimeter is fully functional, as shown in (b). The LED light source (b, left side) and phototransistor detector (b, right side) are secured into the 3D printed colorimeter using a size 000 rubber stopper for this design. More complex designs are available, including 3D printed docks that eliminate the need for rubber stopper docks, if preferred. While simple, this design is a great starting project for new CAD users.

Wiring diagrams are provided above for both allegator clip-terminated lead wires and a breadboard setup. These are covered in my previous colorimeter Instructable projects.