CADStack - CAD Automation Skill Pack

Generate, execute, and verify CAD scripts across FreeCAD, AutoCAD, SolidWorks, and Fusion 360 using natural language commands with safety checks.

Security Scan

The skill's code and runtime instructions largely match a CAD automation tool, but there are several mismatches and operational risks (missing install spec vs. a shipped setup script, instructions to run unknown ./setup, local COM/FreeCAD access) that warrant caution before installing or running it.

Purpose & Capability

The name/description (multi-backend CAD automation) matches the included Python backends (FreeCAD, CadQuery, AutoCAD, SolidWorks, Fusion). Having COM-based backends and a pure-Python CadQuery/FreeCAD backend is appropriate for the stated purpose. However, the SKILL metadata claims 'No install spec — instruction-only' while the package contains many implementation files and a setup script referenced in SKILL.md, which is an inconsistency.

Instruction Scope

SKILL.md explicitly tells users to git-clone a repo and run ./setup, and the skill is designed to 'detect & configure' local CAD backends. That means the runtime can (and code does) interact with local COM objects (AutoCAD/SolidWorks), FreeCAD Python API, and filesystem paths (e.g., ~/.claude/.../output). Instructions give the agent broad leeway to detect and configure local tools and to read/write files under user home dirs — actions beyond a pure API wrapper and which can access sensitive local state if misused. The README's example clone URL is a placeholder (https://github.com/user/cadstack.git), adding uncertainty about origin.

Install Mechanism

Registry lists no install spec, but SKILL.md references a setup script (./setup) and the file manifest includes many code files — this mismatch means installation may require executing the included setup script on the user's machine. Running an arbitrary setup script from an unknown source is high-risk: it can modify system files, install packages, or start services. No vetted package source (official release host) is declared.

Credentials

The skill declares no required environment variables or credentials, which is reasonable for local CAD automation. However, the code will interact with local OS services (COM via pywin32 on Windows), local FreeCAD installations, and create output under user paths. Those capabilities are proportionate to CAD automation but do mean the skill can access local files and running applications — the registry declaration does not call this out explicitly.

Persistence & Privilege

always:false and model invocation defaults are ordinary. The package includes a setup script and configuration skills (/cad-config) that imply it may write configuration under ~/.claude or similar; that is normal for a skill that configures local backends, but it represents filesystem persistence and should be reviewed. The skill does not explicitly claim to modify other skills' configs, but the presence of a setup script means it could.

What to consider before installing

Do not run the referenced ./setup or otherwise install this skill until you have verified its origin and reviewed the setup script and code. Specific steps to follow before installing: - Verify source: SKILL.md suggests git cloning from GitHub, but no official homepage or canonical repo is provided. Confirm the repository URL and owner identity (the placeholder URL in README is suspicious). - Inspect ./setup: open it in a text editor and confirm it only installs expected Python packages and places files in safe locations. Refuse to run setup if it runs arbitrary shell commands, curl|sh patterns, or downloads/extracts archives from unknown hosts. - Audit code that interacts with the system: review files that import win32com, FreeCAD, or that write to home directories. These will access local CAD applications and files and can be abused to read local data or control COM-enabled applications. - Run in an isolated environment first: if you want to test, run the skill in a VM or disposable container with no access to sensitive files, or use a non-production machine with CAD licenses as needed. - Confirm network behavior: search the code for outbound network calls, hard-coded endpoints, or telemetry. If the skill needs a bridge/add-in (e.g., Fusion 360 bridge), verify how that add-in is installed and whether it opens network ports or external endpoints. - Principle of least privilege: only enable the backends you need (prefer CadQuery or FreeCAD headless) and avoid enabling AutoCAD/SolidWorks COM automation unless necessary. If you cannot perform these checks yourself, treat the skill as untrusted and avoid executing its setup script or invoking it with access to production data or local credentials.

CAD Automation Skill Pack

Control AutoCAD, SolidWorks, Fusion 360, and FreeCAD via Claude Code skills.

Why CADStack?

The problem: CAD tools require precise commands. Want a 10mm hole? You need to know the exact API call, parameter order, and coordinate system.

The solution: Describe what you want in natural language. CADStack generates the CAD script, validates it for safety, executes it, and verifies the output.

Traditional CAD:                    CADStack:
─────────────────────────────────    ─────────────────────────────────
1. Open CAD software                1. /cad "bracket with 4 holes"
2. Create sketch                      → Generated script
3. Draw rectangle                      → Safety validated
4. Add dimensions                      → Executed
5. Extrude                             → Dimensions verified
6. Create hole sketch                2. ✓ Done
7. Draw circle
8. Cut extrude
9. Repeat 3 more times
10. Export STEP

What makes CADStack different:

• Safety-first: Every script reviewed before execution
• Multi-backend: Same commands work across FreeCAD, AutoCAD, SolidWorks, Fusion 360
• Verification built-in: /cad-qa confirms dimensions match your intent
• Headless mode: FreeCAD works without opening a GUI

Available Skills

Skill	Description
/cad	Primary skill — Execute CAD commands: create, modify, export parts
/cad-plan	Plan complex multi-step CAD operations before execution
/cad-review	Review generated CAD scripts for safety/correctness
/cad-qa	Verify exported files, check dimensions, validate geometry
/cad-config	Set up and configure CAD backend connections

Which Skill to Use?

┌─────────────────────────────────────────────────────────────┐
│                    CADSTACK DECISION TREE                    │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  START                                                       │
│    │                                                         │
│    ▼                                                         │
│  "Is this your first time?" ──YES──► /cad-config            │
│    │                                (detect & configure)    │
│    NO                                                        │
│    │                                                         │
│    ▼                                                         │
│  "Simple operation?" ──YES──► /cad                          │
│  (single part, 1-3 steps)       (create, modify, export)    │
│    │                                                         │
│    NO                                                        │
│    │                                                         │
│    ▼                                                         │
│  "Multi-step or assembly?" ──► /cad-plan ──► /cad           │
│                                 (plan first)   (execute)    │
│                                                              │
│  AFTER /cad:                                                 │
│    • Need to verify output? ──► /cad-qa                     │
│    • Review script safety?  ──► /cad-review                 │
│                                                              │
└─────────────────────────────────────────────────────────────┘

Quick reference:

• Just want to make a part? → /cad
• Building something complex? → /cad-plan then /cad
• Not sure it worked? → /cad-qa
• Setting up for the first time? → /cad-config

Supported Platforms

• FreeCAD (Recommended) - Pure Python, headless mode, no license required
• AutoCAD - Requires AutoCAD running, uses COM automation
• SolidWorks - Requires SolidWorks running, uses COM automation
• Fusion 360 - Requires Fusion 360 running with bridge add-in

Quick Start

# Install cadstack
git clone https://github.com/user/cadstack.git ~/.claude/skills/cadstack
cd ~/.claude/skills/cadstack && ./setup

Then in Claude Code:

/cad "Create a 100x50x20mm box with 5mm filleted edges"

First Run Experience

If this is your first time using cadstack, follow this sequence:

Step 1: Verify setup
┌─────────────────────────────────────────┐
│ /cad-config                             │
│                                         │
│ ✓ FreeCAD: available                    │
│ ✓ Output dir: ~/.claude/.../output      │
│ ✓ Default format: STEP                  │
└─────────────────────────────────────────┘

Step 2: Hello World (builds confidence)
┌─────────────────────────────────────────┐
│ /cad "create a 10mm cube"               │
│                                         │
│ ✓ Created: output/cube.step (2.1 KB)    │
│   Dimensions: 10 × 10 × 10 mm           │
└─────────────────────────────────────────┘

Step 3: Your first real part
┌─────────────────────────────────────────┐
│ /cad "create a 50×30×5mm plate with     │
│       four 5mm holes at corners"        │
└─────────────────────────────────────────┘

User Journey Storyboard

Step	User Action	User Feels	Skill Supports It
1	Install cadstack	Uncertain: "Will this work?"	/cad-config verifies setup
2	Create first cube	Relieved: "It works!"	Simple 10mm cube example
3	Create real part	Curious: "What else can I do?"	Examples in /cad skill
4	Complex operation	Confident but cautious	/cad-plan for structure
5	Verify output	Certain: "It's correct"	/cad-qa confirms dimensions
6	Error occurs	Frustrated	Minimal error → recovery command
7	Fix and retry	Satisfied	Clear path forward

Architecture

cadstack/
├── SKILL.md                 # This file
├── setup                    # Installation script
├── skills/                  # Skill definitions
│   ├── cad.md
│   ├── cad-plan.md
│   ├── cad-review.md
│   ├── cad-qa.md
│   └── cad-config.md
├── lib/                     # Core library
│   ├── cad_executor.py      # Script executor
│   ├── backends/            # Platform backends
│   └── utils/               # Helpers
└── templates/               # Script templates

Configuration

Add to your project's CLAUDE.md:

## cadstack
Available skills: /cad, /cad-plan, /cad-review, /cad-qa, /cad-config
Supported platforms: FreeCAD, AutoCAD, SolidWorks, Fusion 360
Default platform: freecad