Ask an AI assistant about TrussLab

What this page is for#

TrussLab is intentionally different from ordinary CAD. The hard part for a new user is often not finding a button; it is understanding the model: logical nodes and links first, stock members for length, printed attachments and joints for local complexity.

This page gives general-purpose AI assistants a compact operating manual. Copy the context, paste it into ChatGPT, Claude, Codex, or another assistant, then ask practical questions about what you want to model.

The same context is also available as plain Markdown at agent-context.md, and agents that look for site indexes can start from llms.txt.

Copy the context#

Use the copy button near the top of this page when you want to bring an assistant into a TrussLab session. The copied text tells the assistant what TrussLab is, what it can and cannot do, how presets, autoplay, transaction history, and reconciliation work, and how to answer modeling questions responsibly.

After pasting it into your assistant, ask for a concrete workflow rather than a generic explanation. Good questions mention the object, scale, stock material, printed material, expected loads, mounting constraints, and whether you want to start from a preset.

For a guided explanation of the design model, read Understand the model. Use Getting Started for a short first session and Exporting and preparing a build for manufacturing output.

Choose the Attachment Editor guide for parametric CSG authoring, or the Foreign Part Editor guide for editable mate interfaces on purchased geometry. The Learn hub introduces all three editors together.

Good questions to ask#

• How would I model a small wall-mounted camera arm from stock tube and printed joints?
• Which preset is closest to a lightweight drone frame, and what should I change first?
• I want to make a rectangular fixture frame with diagonal bracing. What TrussLab concepts do I need?
• When should I use a physical link attachment instead of a virtual link attachment?
• How should I think about reconciliation before exporting parts for printing?
• How can I use the transaction log to try full-frame reconciliation safely?
• How do I import my own motor mesh and mate it to a printable mount?
• How do I send one editable model without replacing the recipient's workspace?
• What should I verify before treating this exported model as build-ready?

How assistants should answer#

An assistant should explain TrussLab in terms of the editor's real concepts: nodes, logical links, physical links, attachments, foreign parts, assembly mates, attachment connections, attachment offsets and end pinning, reconciliation, transaction log, presets, autoplay, properties, and export.

For modeling questions, the assistant should first classify the task. Is the user trying to design the overall frame, a printable attachment, a purchased-part definition, a connected joint, or a finished physical assembly? Then it should propose a short sequence of editor actions and name the parts of the model that should stay parametric.

When a preset is close, the assistant should recommend starting there, watching or scrubbing the narrated autoplay, taking over at the relevant step, and changing properties before moving individual geometry.

Conversational modeling with MCP#

For the technical explanation and a concrete parametric example, read Design parametric frames with your AI agent. It explains structural operations, native expressions, focused inspection, atomic edits, and the shared editor implementation.

TrussLab Pro supports connections through MCP (Model Context Protocol) so you can model through a conversation with your preferred coding agent. Describe the structure you need, let the agent choose suitable attachments and create a parametric frame, then refine it over subsequent turns. The result stays editable in TrussLab, with normal parameters, materials, attachments, and history.

For example, start with “Create a triangulated desk stand with flat feet and mounts for a round top; make its height, width, and tube diameter parametric.” Continue with “Make it taller,” “Use black joints and aluminium tubes,” or “Keep this version and try a wider base.” The agent can group related changes into one undo step and use named branches or checkpoints to explore alternatives.

Hosted MCP is deployed for enrolled, signed-in Pro accounts. Follow Install TrussLab MCP or give your coding agent the plain Markdown setup guide. Complete OAuth sign-in, then approve the matching connection in your chosen editor tab. Hosted requests and selected model results pass through the TrussLab relay and your agent provider; model storage and execution remain in the browser. You use your own coding agent and its model access. Copying this page's context provides guidance; direct editing requires a connected MCP session.

Attachment Editor sessions let the agent inspect and edit the reusable CSG design, parameters, bodies, ports, clearances, and history. Ask it to read topics authoring and attachment-editing. Current-attachment consent covers that open document; workspace consent is needed for creation, opening, and publication. Existing Frames adopt a later published attachment version only through an explicit catalogue update.

Foreign Part Editor sessions expose typed mounting interfaces, diagnostic keep-outs, mesh registration, mass, publication, and GLB/editable-package transfer. Ask the connected agent to read topic foreignParts. Document-only consent covers that foreign part; workspace consent is needed to create/import other documents and assign a published exact release to a Frame.

For purchased-part instances in a Frame, read foreign-placement. Choose Absolute, Mate, or On-guide; On-guide follows an existing node and virtual link with reactive offset and local rotation. It can share a pivot and own mated children. Flip direction reverses the guide basis and offset direction without rewriting expressions. For attachments and guided foreign parts, the Flip icon is highlighted when facing opposite the parent link and its tooltip reports the direction. Detach from guide preserves the current world pose as Absolute. UI Move retains guide adjustments; SDK/MCP onGuide replaces them and defaults omitted values to zero/false. Current mates describe fixed installation with optional axial clocking. Use relative nodes and On-guide for sliding and articulated mechanisms. Older pinned sliding/spherical mates retain their formulas and behavior. See foreign-part placement.

The Foreign Part Editor guide covers the same workflow by hand, including mesh units, publication, and Frame catalogue assignment.

Shaped link ends#

Assistants can help prepare a welded frame with mitered or coped stock ends. In the reconciliation controls, choose pairing and order, then switch Fitted link ends on for the joint. The toggle reconciles final seams immediately; pairing and drag-and-drop order stay editable and determine the miter/coping geometry. Compatible circular, rectangular and L/T/I/U profiles share the same rules. The uniform central member remains separate in the scene; manufacturing export assembles it and its shaped ends into one part.

Introducing new shaped ends requires Pro, including adding a second end to an already treated member. Existing treatments remain editable and removable on Free; history, imports, mesh export and archives preserve them.

A connected agent should read MCP topic shaped-ends, discover frame.setJointFittedLinkEnds and frame.setDefaultFittedLinkEnds, and load the checked shape-tube-ends example. Per-end SDK authoring remains available. The command uses the current inspected physical seam terminal and the original logical guide. Both members of an intended miter are enabled in one batch. Inspect startEndSection/endEndSection to confirm intent; do not author the cuts as attachment CSG or invent end lengths. Native geometry edits maintain treated joints while end meshes regenerate asynchronously.

History-aware guidance#

Assistants should treat the transaction log as a normal part of the TrussLab workflow. Users can try complicated modeling actions, inspect the result, and use Undo/Redo or return to an earlier history step if the change is not better.

For hosted orientation, inspect the child's rotation mode and roll offset before editing. Independent ignores parent roll; Follow parent preserves the relative angle and allows edits; Locked to parent preserves it and prevents local edits. Required non-circular profile alignment overrides attachment controls. Connected agents can read instruction topic rotation and use the generated SDK/MCP setters; angular offsets use degrees about the parent's ordered axis.

Rotate in plane with… is available on Virtual links. Pick another visible Virtual link containing a terminal node of the source, at an end or inside the reference. Their directions define the plane, and collinear pairs are ineligible. The nearest roll places the source's yellow marker in that plane, independently of reference roll. SDK/MCP expose rotateVirtualLinkInPlaneWith({key, reference}). Descendant rotation policies still apply, and no reference dependency is retained.

Editing after undo retains the former continuation under Previous alternatives. Restoring an alternative selects that history without deleting the other path. See the Transaction history reference.

To rehost a configured Physical or Virtual attachment, select it and choose Move. Hover a compatible link near a green target ring, then click. Only destinations accepted with its existing settings and relationships appear; the click finishes the move. The SDK exposes the same operation as frame.physicalAttachment.move({ key, link, node }) and frame.virtualAttachment.move({ key, link, node }).

This is especially useful for risky-looking operations such as full-frame reconciliation, changing a joint strategy, moving attachments, or sweeping a parameter through several values. The right advice is often: try the operation, inspect the generated links, joints, and clearances, then use Undo/Redo or continue from an earlier history step.

Plans and current availability#

TrussLab is free while in beta. The planned paid launch separates Free Personal from TrussLab Pro: Free Personal keeps account-free local modeling and the core STL/3MF print-and-build workflow for personal, non-commercial projects; the initial Pro offer adds commercial-use rights, STEP export, the complete supported profile family, shaped link ends, and unlimited model complexity by plan. MCP access requires Pro and does not require Pro Cloud. A separate Pro Cloud tier is planned to include everything in Pro plus automatic cloud backup/recovery and cross-device sync within a defined storage allowance. Local Pro and MCP do not require Pro Cloud.

Assistants must distinguish roadmap packaging from current availability. Enrolled users can sign in with an email link, and Pro access enables STEP export, solid/hollow rectangular stock (including square dimensions), solid L/T/I/U sections, and new shaped link ends. Existing non-circular members and shaped ends remain editable without Pro. Signing in does not upload or sync documents. Self-service signup and purchase, published complexity limits, and model sync remain planned. Final Pro and Pro Cloud pricing, Free Personal model allowances, cloud storage allowances, legal terms, and effective dates have not been published. Do not invent those details or tell a user that a planned feature is already available.

STEP export is available to signed-in Pro accounts in the Frame and Attachment editors and currently requires an online account response. Export processing stays local. Frame STEP assemblies preserve positioned components: each physical link is one connected CAD solid, including both fitted ends where enabled, while joints and purchased parts use faceted surfaces. Standalone attachments export as faceted surfaces. Do not promise recovered analytic joint surfaces or claim compatibility with a particular CAD application without testing it. STL/3MF export remains available without Pro. See Exporting and preparing a build for format and mesh-detail choices, and Fit stock and export STEP solids for the fitted-stock workflow.

Use TrussLab app for ordinary modeling, sign-in, and MCP. TrussLab demo includes every app preset plus showcase examples and runs anonymously without accounts or MCP. Prefer app for shared presets. Move a demo model into app through editable model export and ordinary import.

For sharing, distinguish an editable snapshot, optional construction-path history, and a complete workspace backup. Ordinary import adds selected models; restoring a backup replaces the workspace. Frame dependencies remain exact, but do not become separately editable attachment or foreign-part documents. See editable model sharing.

Limits and verification#

AI assistance is useful for orientation and workflow planning, but it is not a structural certification tool. TrussLab does not currently replace engineering judgment, physical testing, load calculations, material choice, printer process validation, or inspection of exported geometry.

Before building anything that carries meaningful load, verify the design yourself. Check member lengths, clearances, printed part strength, fasteners, mounting surfaces, print orientation, material behavior, and the consequences of failure.