LuaCAD: Parametric Design for Coders

Ever feel like your mouse-based CAD software is fighting you? When you need to change a single dimension and suddenly your entire assembly breaks, you know the pain of manual modeling. Parametric CAD changes the game by treating geometry as code.

The approach: Geometry as logic

Instead of drawing shapes, you describe them. By using a programming language—in this case, Lua—you define variables for dimensions, offsets, and counts. If you need to make a box wider, you just update a variable. The software recalculates the entire model instantly, ensuring your design remains consistent.

Steps to get started

1. Define your primitives: Start by declaring base shapes like cubes or cylinders using Lua functions.
2. Apply transformations: Use functions to rotate, translate, or scale your objects in 3D space.
3. Perform boolean operations: Combine your shapes using union, difference, or intersection to carve out complex forms.
4. Export: Once your script renders a shape you like, export it to standard formats like STL or 3MF for 3D printing.

Pitfalls to avoid

• Over-nesting: Deeply nested function calls make debugging geometry a nightmare. Keep your logic flat.
• Ignoring units: CAD engines are sensitive to scale. Define your units clearly at the top of your script to avoid ‘tiny object’ syndrome.
• Hardcoding values: If you find yourself typing the same number twice, turn it into a variable. That’s the whole point of parametric design.

Minimal example

local box = box(10, 10, 10)
local hole = cylinder(2, 12)
-- Subtract hole from box
local part = difference(box, hole)
render(part)

Your next move

Pick a simple object you’ve made before—a phone stand or a bracket—and try to recreate it in LuaCAD. Focus on making it ‘parameterized’ so that changing one variable adjusts the entire piece. You’ll never go back to clicking and dragging again.