Generative design: make it lighter, still strong

Most parts carry their load along a few paths; the rest of the material is along for the ride. Generative design finds those paths for you. It starts from your part and the way it's used (where it's held, where the load goes), removes the material the load doesn't need, and checks every result with the same simulation you use for “Will this hold 5 kg?”.

Three ways to start

• Type it: “make this lighter but still hold 5 kg”, “lighten it but keep it strong”, “topology optimise this bracket”. The agent reads the load from your words and the shape (where it's held, where the load sits, which way it pulls) and offers the study with that setup — confirm the credits and it runs, or press Adjust to look at the setup first.
• From a simulation result: press Make it lighter on the result card. The study uses exactly that load case.
• ⌘K → Generative design… opens the setup for the active piece.

The setup

• Load case — from the simulation: where it's held, where the load goes, how much, the material. Change faces in Simulate… opens Pro mode to pick other faces.
• Goal — Lightest that holds (keep a safety factor of at least 2, or what you choose), or Stiffest at a mass (keep, say, 40 % of the material and make it as stiff as possible).
• Design space — Inside the piece (material can only be removed), or A box around it (material may also grow where the part isn't today — never behind a flat face it is held by, never over a flat face the load rests on, and never into a screw hole). A box result replaces the part: your original steps stay in the Recipe, switched off, so you can go back.
• Keep — the held and loaded faces stay solid with a margin behind them, and so does the material around mounting holes. Keep-out boxes stay empty (a cable, a mating part, a screwdriver path).
• Made by — for 3D printing (FDM) the optimiser avoids overhangs steeper than 45° from the print direction (so the result prints without supports) and nothing thinner than twice the nozzle. Choose the print direction; it starts from the piece's print orientation. Any process drops those rules.
• Mirror-symmetric across X, Y or Z, if the part should stay symmetric.
• Resolution — Draft (about 40 s), Standard (about a minute) or Fine (about a minute and a half, more detail).

While it runs

You watch the shape grow: the optimiser starts from a uniform part and moves material to where the load needs it, iteration by iteration. The panel shows which mass target it's on, the current mass and how the stiffness converges. Stop ends the study; outcomes that were already verified stay. You can leave the view — the study keeps running, and ⌘K → Show the last generative design study brings it back.

The outcomes

You get 2–3 outcomes at different weights (for example 60 %, 47 % and 34 % of the original mass). Every outcome was rebuilt and re-simulated with your load case before you see it: the card shows its weight against the original, the safety factor (and whether it reaches your target), and how far it bends. The lightest one that holds is marked Recommended.

Each outcome comes in two forms — switch between them on the card:

The fixture faces, loaded faces and mounting holes of the organic shape are your original faces, exactly — the organic body is intersected with your part, so screws still fit and the same simulation load case still applies.

On each card:

• Use as the piece applies it (one step in your Recipe; undo works as usual).
• Open as branch puts it on its own branch so you can compare or merge it later in History (Maker plan and up).
• Add to Variants puts it next to other versions in the Variants view, with weight, stiffness, print time and cost side by side.

“Try 3 lighter versions” in Variants also includes an optimised version made this way when your plan includes the full simulation.

Plans and credits

Generative design runs on the full simulation, so it comes with Pro and Team. A study costs 30 AI credits, charged only when it delivers at least one verified outcome (see Credits explained). If nothing can be built and checked, nothing is charged.

How it works

The optimiser is SIMP topology optimisation on the simulation's grid of small cubes: every cube gets a density between empty and solid, the stiffness of the part under your load is computed (the same finite-element solver as the simulation), and densities move toward where they make the part stiffest for the material allowed. A filter keeps members a printable thickness; for FDM an overhang filter only counts material that has something under it. The result is turned into a smooth closed surface (marching cubes, smoothed and simplified), checked to be watertight, and intersected with your part.

Good to know

• It is as good as the load case. A part that is used in several ways (hung and also knocked sideways) needs those loads too — add them in Simulate.
• The optimiser works at the simulation's resolution (a few millimetres on a hand-sized part). Very thin features (under about two grid cells) aren't resolved; Fine helps.
• Mass targets never go below the faces you keep: if the kept faces are a large share of the part, the lightest outcome is heavier.
• As with any simulation: print one and test it for parts that matter.