Writing a custom feature

A custom feature is your own smart feature: a small TypeScript program that takes typed parameters and adds recipe steps. Once saved, anyone in the workspace inserts it from ⌘K in any Thing. Its parameters become a dialog with a live preview, and in the Recipe it reads as one sentence, like "3 × 2 Gridfinity bin, 6 units tall", with its numbers as editable chips.

Think of it as FeatureScript, in TypeScript, using the same calls as the script view.

Start one

Open Workspace → Custom features (or ⌘K, Custom features) and press New feature for a small example, or Start from the Gridfinity example for a real one. The editor checks your code as you type, in the same sandbox the build uses, and shows two things on the right:

• The dialog: the parameters you declared, as people will see them.
• Steps it adds: what one run with the defaults produces.

Press Save version when it works. Each save is a new version (v1, v2…). Steps already in a recipe keep the version they were made with.

The shape of a feature

export default feature({
  name: "Peg row",
  description: "Pegs in a row on top of a part.",
  summary: "{count} pegs, {spacing} mm apart",
  params: {
    count: number({ label: "Pegs", default: 4, min: 1, max: 20, integer: true }),
    spacing: length({ label: "Spacing", default: 15, min: 2 }),
    diameter: length({ label: "Diameter", default: 4 }),
    square: boolean({ label: "Square pegs", default: false }),
  },
  build(p, ctx) {
    const z = ctx.bbox ? ctx.bbox.max[2] : 0;
    for (let i = 0; i < p.count; i++) {
      const x = (i - (p.count - 1) / 2) * p.spacing;
      if (p.square) box("peg_" + i, { size: [p.diameter, p.diameter, 6], position: [x, 0, z + 3] });
      else cylinder("peg_" + i, { radius: p.diameter / 2, height: 6, position: [x, 0, z] });
    }
  },
});

• summary is the Recipe sentence; {name} is replaced by the parameter's value.
• build(p, ctx) receives the parameters already evaluated (millimetres and degrees, even when the person typed a formula like width / 2). ctx.bbox is the bounding box of what's built so far (or null), ctx.hasBody says whether there is anything yet, and ctx.warn("…") adds a note to the step.

Parameter types

Each takes label, default, an optional help line, and for numbers min, max and step. Values outside min/max are refused in the dialog and in the build, with your label in the message.

Building blocks

Everything from the script view: sketch, extrude, revolve, sweep, loft, primitive, shell, fillet, chamfer, draft, hole, pattern, mirror, boolean, rib, transform, offsetFaces, split and the built-in smart features through macro(…); planes XY(), XZ(), YZ(), onFace(selector); shapes rect, circle, ellipse, polygon, slot, path (with line, arc3…); selectors topFace(), faces(…), edges(…). Two shortcuts: box(id, { size, position }) and cylinder(id, { radius, height, position }). Plus plain JavaScript: loops, Math, functions.

Step ids are local: write sketch("base", …) and extrude("body", { sketch: "base", … }). Solid Vibes prefixes them with the step's id, so the same feature can be used twice in one piece.

The sandbox

Custom features run in a separate JavaScript engine (QuickJS, compiled to WebAssembly) in your browser and on our geometry servers:

• No network, no page, no files. There is no fetch, window, document, process or require; import is not available.
• Same result every time. Date is not available and Math.random() always returns the same sequence, so builds can be cached and replayed.
• Limits. 1.5 seconds and 32 MB per run, at most 500 steps. An endless loop is stopped with a clear message on the step.

The code travels inside the recipe step, so commits, exports, the server and remixes all build it without looking anything up.

Share it

• Everyone in the workspace can insert it from ⌘K.
• Publish to Marketplace (on the feature's page) releases it as a Feature listing, shown with an example Thing built with its defaults. Others press Add to my features on the listing to get a copy in their workspace, and can read its code first.
• Plugins can bring custom features with them (the Gridfinity bin generator does).