Agentic CAD · Rhino 8 plug-in · 2025 – 2026

STF
Agent.

From a written brief or a reference image, the agent builds native, layered geometry inside Rhino and verifies its own output.

C# · .NET 7 · RhinoCommon · Grasshopper
41 modelling tools · Claude, OpenAI, Gemini

View the interactive panel

Interactive panel below
Loading frames…

Skyweave · frame by frame

Built frame by frame.

The real sequence from the Skyweave session: every frame is the Rhino document as the agent left it. The scrollbar is the timeline.

Site → massing

The plot, then the volume.

The empty plot and its neighbours first; the tower’s massing is established before any detail is drawn.

Floors → skin

Layer by layer.

Floor plates, screens, glazing and gardens arrive in the order they were modelled, one tool call at a time.

Review

Exploded for review.

The finished model, exploded so every layer can be checked before it is handed back.

Interactive

Interface demonstration.
Simulated Rhino host.

A demonstration of the plug-in interface running against a simulated Rhino host. It presents the interaction design only. Select a brief to view the plan, tool calls, stages and viewport capture as they are presented in the panel.

A custom brief can also be entered in the panel. The demonstration runs entirely within the browser.

STEF · Rhino 8 · docked panel

How a turn works

Planning precedes geometry.

A request is checked, sized and planned before any geometry exists. Then it is built in visible steps, verified by measurement rather than by eye, and closed as a single undo step.

  1. 01RequestA brief, typed or spoken, with optional images or PDFs attached.
  2. 02Pre-flightThe request is validated: attachments, model capabilities and the cost limit are confirmed, and an undo record is opened.
  3. 03ContextThe agent receives its instructions, the state of the open Rhino document and the rules for the turn.
  4. 04Read the referenceAttached images or drawings are measured and written up as a specification before any geometry is drawn.only when images or PDFs are attached
  5. 05Size the jobThe scope is assessed: small, well-defined requests are executed directly; larger or open-ended ones are planned first.
  6. 06PlanThe work is divided into six to nine named stages with a short construction strategy.
  7. 07Build loopIn each round the agent chooses one operation, calls the matching modelling tool and reads back the result.up to 40 rounds per turn
  8. 08VerifyClosed solids, layers and dimensions are checked by measurement, and viewport captures are reviewed before the model is returned.
  9. 09CheckpointWhere a design decision is required, the turn pauses and waits for a reply.only when the next stage needs a decision
  10. 10FinishA short summary is returned, the turn is recorded as a single undo step and the conversation is saved.
one round · up to 40 a turn result · object ids · count · error · capture Panelrequest · scene · tools Modelone sentence · one tool STF plug-inruns the tool in Rhino Rhino 8geometry · repaint result · ids · count · error · capture one round · up to 40 a turn Panelrequest · scene · tools Modelone sentence · one tool STF plug-inruns the tool in Rhino Rhino 8geometry · repaint
The build loop. Each round the model says what it will do in one sentence and calls one tool; Rhino’s result decides the next round.
an operation is needed does one of thetyped tools match? yes no use the toolvalidated · fails with a reason conical roofrevolve 72 rafterspolar_array a slabcreate_box write Pythononly when no tool fits 756 bricksa pattern 20 partitionsa rule voxel fieldan algorithm
Tools first. Typed tools fail loudly and touch only what they are given; Python is the fallback for what no tool covers.

In use

Examples.

Recorded sessions in Rhino 8, shown at full size, with no cuts inside a turn.

Skyweave · a tower study developed with the agent at STF Labs: massing, screens, glazing, gardens, core.
Villa floor plan · rooms, furniture, pool and landscape drawn as layered curves in the plan view, one stage at a time.
Stadium · modelled from one prompt, live in the docked panel.
Tower on a Canary Wharf plot · from a map capture and a reference image.
“Model the Vessel” → “Make it parametric in GH” · hex stair lattice from reference images, then a Grasshopper definition.
Mixed-use block · slabs, columns, facade module and layers in one turn.
Bridge · form, then a space-frame truss over the deck.
Grasshopper target · components placed and wired by the agent.