Chat-driven design

Most CAD tools start with a blank canvas. Prompt2CAD starts with a conversation. You describe the piece, the agent asks what it needs to know, you approve a plan, and the agent writes geometry code that the viewport renders live.

This page is the mental model. If you understand the four stages, every weirdness in the app starts to make sense.

The four stages

1. PROMPT  →  2. PLAN  →  3. BUILD  →  4. REFINE

1. Prompt

You type what you want. The agent reads your message in the context of the entire conversation so far — previous prompts, previous models, previous decisions all carry forward. There is no "reset on every message" model; the conversation is the design.

2. Plan

Before writing any geometry, the agent will typically ask one to three clarifying questions and then show a plan:

• Overall dimensions (width × height × depth).
• A bubble diagram or sketch of the major elements.
• Style direction (Scandinavian, mid-century, shaker, industrial, …).
• Structural notes (back panel, plinth, hardware visibility).

The plan appears as an inline panel in the chat with an Approve button. Approve to proceed, or paste a follow-up to change direction. You can also skip the plan step for trivial follow-ups; the agent uses its judgement.

Why ask before building?

Building geometry is the expensive step (30 credits, 20–60 seconds). A two-line plan that surfaces a misread costs nothing and saves a generation.

3. Build

Once the plan is approved (or skipped), the agent assembles the model — laying out the structure, picking materials, and declaring the sliders you will use to adjust it. The viewport builds the scene live as the agent works.

You will see one Write geometry card in the chat covering the build. Click it to expand the details if you're curious; otherwise just watch the model appear.

4. Refine

This is the loop you spend most of your time in. Two ways to refine:

• Sliders — every adjustable knob the agent declared appears in the Parameters panel. Dragging a slider re-renders the model locally with the new value. No credit cost, instant.
• Follow-up prompts — anything sliders cannot cover. The agent either makes a targeted edit to the existing model or rewrites the relevant section from scratch, depending on what your prompt asks for. Costs 15 credits per iteration.

Iterate freely. The agent retains the design state, the project history, and any past screenshots, so you can say "go back to the version with three drawers" and it will know what you mean.

What the agent can do

The agent has the basics you would expect of a model-building assistant: it can shape the model, manage sliders, change materials, snap the camera to a view, take screenshots from any angle, and check measurements and clearances. Each action surfaces in the chat as its own labelled card so you can see what happened.

You almost never need to name an action — describing what you want in plain language is enough. The agent picks the right approach based on your prompt.

Why the agent sometimes "thinks out loud"

The agent occasionally streams a short thinking pass before an action, surfaced as a faded chunk in the chat. You can ignore it — it exists so you can see what the agent is reasoning about if a turn surprises you. It is not billed separately.

What the agent cannot do

A few things are deliberately out of scope:

• It cannot remember between accounts. Each Google account has its own conversation history.
• It cannot read files from your computer (other than images you explicitly attach to a message).
• It cannot browse the web or look up part numbers — it draws on what it already knows about furniture conventions and on the curated material library, nothing more.
• It cannot edit the geometry code while you have an unapproved plan open. Approve or dismiss first.
• It does not produce production drawings. STEP export is dimensionally faithful, but the agent does not produce tolerance callouts, hardware schedules, or BOMs (cut lists are limited and experimental).

Practical takeaways

• Be concrete in the prompt. Dimensions, material, style. Vague prompts get clarifying questions; specific prompts skip straight to the plan.
• Approve plans quickly or push back hard. If the plan looks wrong, say so before the build — once 30 credits are spent, iterating costs 15 each.
• Use sliders first, prompts second. Width, height, drawer count, finish enums — try the slider before asking the agent to "make it a bit wider."
• Trust the conversation. You do not need to repeat context every message. The agent already knows what you are building.

Next: Parameters — how sliders actually work, and why most of your iteration should happen there.