Programming Is the New Modeling: Designing 3D Models with OpenSCAD

If the thought of 3D modeling immediately conjures up images of complicated click marathons in expensive CAD programs, then pay attention: there is another way — and one that requires no mouse acrobatics at all! Welcome to OpenSCAD, the programming language for everyone who prefers typing over drawing. With OpenSCAD, you turn lines of code into precise 3D models that can be exported to STL at the push of a button and then printed on your 3D printer. Sounds nerdy? Maybe. But also pretty brilliant, especially when you consider that the possibilities are nearly limitless and the software is free. In this article, we will take a look at why OpenSCAD is the insider tip for 3D printing enthusiasts and how you can use it to quickly create creative, functional, and perfectly tailored designs.

Let’s get started.

#Installation

There are different methods for installing OpenSCAD depending on your operating system:

• Windows: The easiest method is to download the installer from the official OpenSCAD website. Alternatively, you can install OpenSCAD via the Microsoft Store app, which simplifies future updates.
• macOS: OpenSCAD can also be downloaded directly from the website. The DMG package is downloaded and can be installed by simply dragging the app into the Applications folder. Alternatively, a Homebrew cask is available that enables installation via brew install openscad.
• Linux: For Debian- and Ubuntu-based systems, installation via the package manager is the easiest: sudo apt install openscad. On Fedora-based systems, sudo yum install openscad works. Alternatively, OpenSCAD can be installed via Snap or Flatpak, which works on many distributions and provides versions that are often updated more quickly.
• OpenSCAD can also be downloaded as an AppImage for Linux, which provides a platform-independent option. This file is downloaded, made executable (chmod u+x <filename>), and run directly. For all installation variants and dependencies that may be required depending on your system, it is worth checking the official documentation.

#First Steps

After OpenSCAD has been successfully installed, you can start programming 3D models right away. Unlike conventional CAD programs, you do not draw a design here but describe it through code in an editor window. The result of the code is displayed in a preview window in real time, making the workflow particularly efficient and precise.

Getting to know the interface: After launching OpenSCAD, you will see the main areas of the program.

• Editor window: This is where you write the code that describes your model.
• 3D viewport: A preview of the model that is updated by pressing F5.
• Console: Displays errors and feedback on code execution, which helps with debugging.

Creating a simple object: You can start, for example, with a simple command like cube([10, 10, 10]);. This code creates a cube with an edge length of 10 units in the X, Y, and Z directions. Pressing F5 executes the code and displays the result in the preview area.

Applying transformations: OpenSCAD offers various ways to manipulate objects. The command translate([20, 0, 0]) moves the subsequent object by 20 units along the X axis:

translate([20, 0, 0]) {
   cube([10, 10, 10]);
}

Combining objects: For more complex models, you can combine objects. The functions union(), difference(), and intersection() allow you to merge multiple parts, subtract one from another, or create the intersection. For example, a sphere and a cube can be combined:

union() {
   cube([10, 10, 10]);
   translate([5, 5, 10]) sphere(5);
}

Using parameters: OpenSCAD allows the use of variables to make the size and position of objects flexible, which is helpful when creating parametric models:

cubeSize = 10;
cube([cubeSize, cubeSize, cubeSize]);

With these basics, you can get started right away and create simple 3D models.

The OpenSCAD tutorial on Wikibooks is a comprehensive introduction for beginners and advanced users alike. It covers the fundamental principles of programming 3D models in OpenSCAD and provides step-by-step instructions on the most important commands and functions.

#Practice

In this practical example, I wanted to construct a simple stand for an acrylic sheet. One approach to the construction is to create a polygon with the cross-section of the stand and then extrude it. The whole thing should be parametric from the start, so it can be easily adjusted later.

depth=30;
width = 40;
height = 12;
bevel = 10;
slot_width = 3;
slot_depth = 7;

linear_extrude(height=depth) {
    polygon(points=[
        [0, 0],
        [bevel, height],
        [width/2 - slot_width / 2, height],
        [width/2 - slot_width / 2, height - slot_depth],
        [width/2 + slot_width / 2, height - slot_depth],
        [width/2 + slot_width / 2, height],
        [width-bevel, height],
        [width, 0],
        [0, 0]
    ]);
}

Another approach is to create the base shape of the stand first and then create the slot by subtraction. This approach is somewhat easier to understand and modify, as the slot is treated as an independent object.

depth=30;
width = 40;
height = 12;
bevel = 10;
slot_width = 3;
slot_depth = 7;
epsilon=0.001;

difference() {
    linear_extrude(height=depth) {
        polygon(points=[
            [0, 0],
            [bevel, height],
            [width-bevel, height],
            [width, 0],
            [0, 0]
        ]);
    }
    translate([width / 2 - slot_width / 2,
               height + epsilon - slot_depth, -epsilon]) {
        cube([slot_width, slot_depth, depth + 2 * epsilon]);
    };
};

However, we see a small trick in the code to ensure the slot is truly cut all the way through: we introduce an epsilon that ensures proper subtraction by letting the slot extend minimally beyond the surface. This trick is necessary because OpenSCAD has issues with geometric ambiguities when cuts are “too exact.”

#Rendering and Export

After the model has been created, it can be rendered and exported. The rendering process generates the model in high quality and displays it in the preview. The export is done in STL format, which is supported by most 3D printers.

The STL file can then be converted to gcode for the 3D printer using Cura or another slicer.

And in the end, we have the desired result in our hands:

#With a Little Help from AI…

And it gets even better: since the model is now created with code, AI — for example, ChatGPT — can help us generate this code for our model from a description in natural language!

Here is an example: for a 16x16 Neopixel LED display, we need a grid that separates the individual LEDs from each other so that each LED is more visible on the frosted acrylic surface. We could describe our requirements like this:

For a 16x16 LED display, I need a grid that separates the LEDs from each other.
Create the OpenSCAD code for a 16x16 grid, consisting of 16x16 cutout cells
separated by ridges. The grid should be 5 mm tall, the inner dimensions of
each cell 10 mm x 10 mm, and the ridges between the cells should be 0.5 mm wide.
The outer frame should be 3 mm thick.
Please parameterize the respective values via variables so they are easy to change.
Use the epsilon trick to ensure that the cells are truly cut all the way through.

The result is convincing:

Here too, the principles and best practices of prompt engineering help us:

• Goal definition: Clearly and unambiguously define what should be achieved (and that is often not so easy).
• Context: Provide relevant background information, including the purpose for which the model is needed.
• Clarity: Avoid ambiguity through precise language — clearly state relevant details and requirements.
• Details: Specific instructions to narrow down the result, with hints on how the result should be achieved if applicable.
• Expected format: Clearly specify the format or structure the result should have — in this case, OpenSCAD.

Usually, you need to iteratively refine the description to get the desired result, since descriptions in natural language are often not precise enough, or it is not apparent beforehand which details are relevant or that the description might be ambiguous.

Modeling via code in OpenSCAD thus has yet another advantage: the ability to create models through natural language descriptions, which we can then translate into model code with the help of AI.

#Conclusion

OpenSCAD is a powerful tool for anyone who enjoys programming and creating 3D models. The combination of code and preview enables fast and precise modeling that is especially well suited for parametric designs and prototypes. The learning curve is somewhat steeper than with conventional CAD programs, but the possibilities are virtually unlimited. With a bit of practice and creativity, you can create astonishing models that would be very laborious to model manually.

Additionally, the models are stored as code, which can be perfectly managed in a version control system like Git. This makes it easy to track changes and variants.

Give it a try and let your imagination run wild!