Skip to content

CAD for Mere Mortals

CAD (Computer-Aided Design) is how you tell a computer exactly what shape you want — so a 3D printer, a CNC mill, or a laser cutter can make it real. If the 3D-printing guide was about printing other people's designs, this guide is about drawing your own.

No art degree required. Ideas first, then real models you build and render yourself, in millimeters, with numbers that all check out.

What this guide covers

  • What CAD is — the two worlds: parametric modelers (FreeCAD, Fusion, Onshape, Tinkercad) and code-driven modeling (OpenSCAD)
  • Thinking in 3D — coordinates, units, and the sketch-to-solid idea behind every CAD tool
  • Your first model — installing OpenSCAD and rendering real geometry
  • Sketches and constraints — the parametric way: dimensions instead of eyeballing
  • From sketch to solid — extrude, revolve, holes, fillets
  • OpenSCAD in depth — variables, modules, loops, and parametric parts
  • Measuring and tolerances — calipers, clearance, and why holes print small
  • Designing for FDM — wall thickness, overhangs, orientation, threads
  • Project: the L-bracket — a complete part, designed, exported, and print-ready
  • Exporting and sharing — STL vs STEP vs 3MF, and the units trap
  • Troubleshooting — symptom → fix, including real OpenSCAD error messages

What it doesn't cover

Sculpting organic shapes (that's Blender territory), 2D drafting for construction documents, CAM toolpaths for CNC mills, or advanced surfacing. Those are real skills; they're just beyond this guide's scope. Everything here is aimed at one goal: functional parts you can print on an Ender-style or Bambu-style FDM printer.

How to use this guide

Every OpenSCAD example was rendered with real OpenSCAD 2021.01 before shipping — the geometry is real and the STL files are valid. Check: blocks show what success looks like. Careful: marks steps where a wrong number wastes plastic. Dimensions in the project chapter are the single source of truth; every chapter that references the bracket uses the same numbers.

Chapters

  1. What Is CAD?
  2. Thinking in 3D
  3. Your First Model
  4. Sketches and Constraints
  5. From Sketch to Solid
  6. OpenSCAD in Depth
  7. Measuring and Tolerances
  8. Designing for FDM
  9. Project: The L-Bracket
  10. Exporting and Sharing
  11. Troubleshooting
  12. Glossary

Written to the nine-point writing standard shared by every guide in this series.