OpenSCAD Crash Course

Have a 3D printer but find design software frustrating? OpenSCAD flips the script: instead of dragging shapes around, you write simple code that describes exactly what you want. It sounds odd, but it's faster, more precise, and far more flexible than mouse-driven CAD.

By the end of this guide, you'll have designed and exported your first custom 3D object.

Why OpenSCAD?

• You describe, not draw. Write cube([20, 30, 10]); and you get a perfect 20×30×10mm box.
• Parametric by default. Every dimension can be a variable. Change one number and your whole model adapts.
• Perfect for printing. Generates clean meshes that slice without errors.
• Free and open source. Works on Windows, Mac, and Linux. No subscriptions.
• Designs are just text files. Version control them, share them, collaborate.

Your Secret Weapon: AI

AI assistants are exceptionally good at OpenSCAD because it's a scripting language with predictable patterns. ChatGPT, Claude, and Copilot can generate, modify, and debug scripts on demand.

Just ask things like:

• "Create an OpenSCAD script for a wall-mounted hook, 40mm long, 12mm diameter, curved 80°, with a 60×60mm mounting plate and two screw holes spaced 40mm apart."
• "Add mounting holes to this design." (paste your code)
• "Debug this script — it's not rendering correctly."
• "Make this box have rounded 3mm corners."

You don't need to memorize every function. Learn enough to read and tweak AI-generated code, then let AI handle the heavy lifting.

Install OpenSCAD

Download it at openscad.org/downloads.html for Windows, Mac, or Linux. Package manager shortcuts:

Verify it works: Open OpenSCAD, type cube(20);, press F5. A 20mm cube appears. You just made a 3D model.

The Basic Workflow

1. Write code in the editor
2. F5 — fast preview
3. Tweak and repeat
4. F6 — final render (slower, precise)
5. File > Export > Export as STL
6. Open in your slicer (Cura, PrusaSlicer) and print

Build Something: A Storage Box

Step 1 — Solid block

width = 50;
length = 70;
height = 30;

cube([width, length, height]);

Step 2 — Make it hollow

width = 50;  length = 70;  height = 30;
wall = 2;

difference() {
    cube([width, length, height]);
    translate([wall, wall, wall])
        cube([width - wall*2, length - wall*2, height]);
}

difference() subtracts everything after the first object from the first object. The translate moves the inner box 2mm in on all sides.

Step 3 — Round the corners

width = 50;  length = 70;  height = 30;
wall = 2;  radius = 3;  $fn = 50;

difference() {
    translate([radius, radius, 0])
    minkowski() {
        cube([width - radius*2, length - radius*2, height - 1]);
        cylinder(r=radius, h=1);
    }
    translate([wall, wall, wall])
        cube([width - wall*2, length - wall*2, height]);
}

minkowski() "inflates" the cube by the corner radius — like rounding padding on a CSS box.

Step 4 — Export

Press F6, wait for it to finish, then File > Export > Export as STL. Print open-side up at 0.2mm layers, 15–20% infill.

Essential Commands

// Shapes
cube([20, 30, 10]);           // width, depth, height
cylinder(h=20, r=5);          // or use d=10 for diameter
sphere(r=10);

// Move & rotate
translate([10, 0, 0]) cube(5);
rotate([0, 0, 45]) cube(10);

// Combine, subtract, intersect
union()        { cube(10); translate([8,0,0]) cube(10); }
difference()   { cube(20); translate([10,10,0]) cylinder(h=25, r=3); }
intersection() { cube(20); sphere(r=12); }

Always extend holes beyond the surface — it prevents rendering artifacts:

// Good: hole starts -1 below and extends +1 above
translate([10, 10, -1])
    cylinder(h=7, r=2);  // Box is only 5mm tall

Control smoothness with $fn — use low values while designing (fast), high for final render:

$fn = 30;   // Preview
$fn = 100;  // Final render

3D Printing Rules to Live By

Common Problems

"Object is not a valid 2-manifold" — objects don't quite overlap, or walls have zero thickness. Extend all subtractions beyond boundaries.

Model looks blocky — add $fn = 100; at the top of your file.

Parts don't fit — add tolerance: hole_size = peg_size + 0.3;

Stuck? Paste your code into an AI and ask. It's surprisingly good at this.

Go Further

• Official docs & cheat sheet: openscad.org/documentation.html
• BOSL2 library — professional-grade functions: github.com/BelfrySCAD/BOSL2
• Community: r/openscad

The best first project is something you actually need. Pick a small organizer, a cable clip, a phone stand — something useful. You'll have it designed in an hour and printing by tonight.