Show HN: LuaCAD – Parametric CAD Scripted in Lua

Scriptable CAD with Lua. Write parametric 2D and 3D models in Lua and export them to 3MF, STL, OBJ, PLY, OFF, AMF, or SCAD, or render them straight to a PNG.

LuaCAD embeds Lua 5.4 in a Rust engine that evaluates CSG operations directly (via Manifold) or generates OpenSCAD code for external rendering.

Why Lua?

• Similar syntax as the OpenSCAD language, but better:
  • More powerful
  • More consistent
  • Faster
  • Easily embeddable
• Operator overloading for natural CSG syntax (a + b, a - b, a * b)
• Already used in other CAD software like LibreCAD and Autodesk Netfabb

Example

my_cube = cube { size = { 1, 2, 3 } }

function my_sphere(radius)
  return sphere({ r = radius }):translate(5, 0, 0)
end

model = my_cube + my_sphere(2)

render(model)

module my_cube() {
  cube(size=[1,2,3]);
}

module my_sphere(radius) {
  translate([5,0,0]) sphere(r = radius);
}

union() {
  my_cube();
  my_sphere(2);
}

Getting Started

cargo install luacad         # CLI for running and converting LuaCAD scripts
cargo install luacad-studio  # GUI desktop app with live 3D preview

Or from source, which requires Rust:

git clone https://github.com/ad-si/LuaCAD.git
cd LuaCAD
make install

Both crates vendor their C/C++ dependencies, so no system libraries need to be installed — but a C++ compiler and CMake must be available to build them. luacad builds Manifold and Clipper2; luacad-studio additionally builds OpenCSG, which needs OpenGL development headers (on Debian/Ubuntu: libgl1-mesa-dev, libx11-dev, libxcb1-dev, libxkbcommon-dev, libxrandr-dev, libwayland-dev).

CLI Usage

luacad convert model.lua output.3mf   # Convert to 3MF
luacad convert model.lua output.stl   # Convert to STL
luacad convert model.lua output.scad  # Export as OpenSCAD
luacad watch model.lua output.3mf     # Rebuild on file changes
luacad render model.lua preview.png   # Render to a PNG image
luacad info model.lua                 # Print triangle counts and bounding box
luacad lint model.lua                 # Lint with selene (also takes directories)
luacad run model.lua                  # Execute (side-effects only)

convert and watch infer the format from the output extension; --format <fmt> overrides it, and --via-openscad hands the export to an installed OpenSCAD binary instead of building the mesh with Manifold.

BOSL2

LuaCAD has full support for the Belfry OpenSCAD Library v2, reimplemented in LuaCAD itself, so it renders, previews and exports to a mesh without OpenSCAD or BOSL2 installed:

bosl.cuboid { {40, 40, 40}, rounding = 2 }
bosl.regular_prism { 5, r = 10, h = 25 }
bosl.spur_gear { circ_pitch = 5, teeth = 20, thickness = 5 }

Exporting to .scad still writes the BOSL2 call itself, which keeps the exported file as short as the script that produced it.

Text and Imports

text() outlines a system font into a sketch and text3d() extrudes it in one step, so text becomes real geometry rather than SCAD output:

render(text("LuaCAD", { size = 12, halign = "center" }):linear_extrude(2))

import() reads every mesh format LuaCAD writes and returns a solid you can transform and combine like any primitive; SVG and DXF return a 2D sketch instead, ready to extrude.

Supported Export Formats

• SCAD - OpenSCAD format
• 3MF - 3D Manufacturing Format
• STL - Standard Triangle Language for 3D printing
• OBJ - Wavefront 3D object format
• PLY - Polygon File Format
• OFF - Object File Format
• AMF - Additive Manufacturing File Format

Every value your script returns becomes its own 3MF object, so slicers load them as individually movable parts. Label them with :name(…) to control how they appear in the object list. The other formats cannot express separate objects, so they flatten everything into a single mesh.