Reference

OpenSCAD 3D primitives

Four built-in solid primitives — cube, sphere, cylinder, polyhedron — plus import for bringing in external meshes. Everything else in your model is built from these, transformed, and combined with boolean operations.

cube

Generates an axis-aligned box. Default origin is the box's lower-front-left corner; pass center=true to place the origin at the box's centroid instead.

cube(size, center=false);
cube([width, depth, height], center=false);

Parameter	Type	Description
`size`	number or 3-vector	Edge length (uniform) or per-axis lengths in mm.
`center`	bool	If `true`, centroid is at the origin.

Examples

cube(10);                              // 10×10×10 cube, corner at origin
cube([40, 20, 4]);                     // rectangular plate
cube([40, 20, 4], center=true);        // centered

sphere

Generates a sphere centered on the origin. Pass r OR d (diameter), not both.

sphere(r);
sphere(d=diameter);

Parameter	Type	Description
`r`	number	Radius in mm.
`d`	number	Diameter in mm.
`$fn` / `$fa` / `$fs`	special	Control facet density (see special variables).

Examples

sphere(10);                  // radius 10, default smoothness
sphere(d=20);                // diameter 20 (same shape)
sphere(5, $fn=128);         // silky-smooth showcase render

cylinder

Generates a cylinder or a cone along the Z axis. The base sits at Z = 0 unless center=true, in which case the centroid is at the origin and the cylinder extends from -h/2 to +h/2.

cylinder(h, r | d=D, center=false);
cylinder(h, r1, r2 | d1=D1, d2=D2, center=false);

Parameter	Type	Description
`h`	number	Height in mm.
`r` / `d`	number	Radius / diameter — uniform cylinder.
`r1, r2` / `d1, d2`	number	Bottom and top radii — produces a cone or truncated cone.
`center`	bool	Center along Z if `true`.

Examples

cylinder(h=20, r=5);                // straight cylinder
cylinder(h=20, d=10, $fn=64);       // smoother
cylinder(h=30, r1=15, r2=0);          // pointed cone
cylinder(h=30, r1=15, r2=5);          // truncated cone
cylinder(h=5, d=8, $fn=6);            // hexagonal prism

cylinder($fn=6) = hex prism, $fn=4 = square pyramid base.

Low-facet cylinders are the cheapest way to get polygonal prisms — bolts, knurls, hex sockets — without writing a polygon by hand.

polyhedron

For anything that isn't a primitive — sweeps, parametric meshes, ports of external geometry — build it from raw points and faces.

polyhedron(points, faces, convexity=1);

Parameter	Type	Description
`points`	list of `[x,y,z]`	Vertex coordinates.
`faces`	list of index lists	Each entry lists the points (CW when viewed from outside) of one face.
`convexity`	int	Render hint — max number of front+back surfaces a ray crosses.

Example: a tetrahedron

polyhedron(
  points = [[0,0,0], [10,0,0],
            [5,10,0], [5,5,10]],
  faces  = [[0,2,1], [0,1,3],
            [1,2,3], [0,3,2]]
);

Face winding matters.

OpenSCAD expects face vertex indices in clockwise order when viewed from outside the solid. Wrong winding produces inverted normals, non-manifold geometry, and a warning in the console. The AI CAD agent tends to use linear_extrude over polyhedron for exactly this reason.

import

Pull an existing mesh into the scene. Useful for ingesting community parts, vendor models, or scan data.

import("my_part.stl", convexity=10);
import("frame.3mf");
import("mesh.off");

Supported formats: .stl, .off, .amf, .3mf. 2D variants of import handle .dxf and .svg.

Cookbook

Through-hole plate

difference() {
  cube([40, 40, 4]);
  translate([20, 20, -1])
    cylinder(h=6, d=6, $fn=48);
}

Hemisphere

difference() {
  sphere(10, $fn=96);
  translate([0,0,-10])
    cube([22,22,10], center=true);
}

Bolt blank (M3 × 16)

union() {
  cylinder(h=3, d=6, $fn=6);   // hex head
  cylinder(h=19, d=3, $fn=32);  // shank
}

Rounded plate (Minkowski)

minkowski() {
  cube([38, 28, 3]);
  cylinder(r=3, h=0.5, $fn=32);
}

Need a specific shape? Just describe it.

"M3 corner bracket with 30 mm legs and two countersunk holes per leg" → the AI agent picks the right primitives, transforms, and booleans.

Try a prompt