pattern-making-skill

A garment pattern-making skill for AI agents. It drafts women's, men's and children's blocks from body measurements, transforms them into designs, adds seam allowances and notches, grades sizes, and exports 1:1 SVG, DXF and CLO3D files.

The agent never computes coordinates in its head: every point goes through pattern.py, a single Python file with no dependency, which checks that seams match after each step.

Works with clo3d-mcp-extended

This skill and clo3d-mcp-extended are built to work together. The skill computes the pattern. clo3d-mcp-extended builds it in CLO3D.

	pattern-making-skill	clo3d-mcp-extended
Role	Computes the pattern: measurements, blocks, darts, flare, grading	Drives CLO3D: pieces, seams, fabrics, avatar, simulation, images
Output	SVG, DXF, clo3d_<size>.json with exact Bezier curves and named edges	A garment in CLO3D
Works alone	Yes, for pattern making and the SVG and DXF exports	Yes, for any CLO3D task

Together, the agent drafts the pattern, sends the pieces to CLO3D with one CLO3D line per pattern edge, sews them by edge name, places them on the avatar and simulates. The CLO3D side needs the clo3d-mcp-extended plug-in loaded in CLO3D. Without it, the skill still writes a standalone script to run in CLO3D's Script Editor. See references/clo3d.md.

What it covers

• Analysis first: from a photo, the agent identifies every seam, fold, piece and finish with evidence and confidence before drafting; from a fashion sketch, it works out volumes, proportions and cutting, including sculptural and unconventional shapes.
• Real pattern construction for every family: skirts, trousers, bodices and dart manipulation, dresses, shirts, sleeves, collars, tailoring and outerwear, knits, lingerie, swimwear, gloves, hats, bags, and the sewing techniques behind them (seams, hems, facings, closures, pockets, gathers, elastic).
• Engine: proportional blocks (skirt, bodice, sleeve, trousers), a leather glove block drafted like real glove patterns (trank, Bolton thumb, fourchettes), dart pivot, slash and spread, curve smoothing, pieces with holes, seam allowances, notches, grain lines, grading.
• Checks: every draft reports seam matching, ease, finished measurements. A !! line must be fixed.
• CLO3D: exact Bezier edges, seam lists, one-command assembly through the clo3d-mcp-extended plug-in, sensible defaults (collision thickness 0, mesh size by fit), and hand-over to the user when a piece is too complex to place automatically.

Values that come from trade practice rather than a cited source are flagged in the technique sheets: validate on a toile.

Install

Claude Code, as a plugin:

claude plugin marketplace add adriendelmas/pattern-making-skill
claude plugin install pattern-making@pattern-making-skill

Any agent that reads skills (Claude Code, Claude apps, Codex, opencode, Cursor and others): copy the folder skills/pattern-making into the agent's skills folder, for example ~/.claude/skills/.

Agents without skill support: give the agent skills/pattern-making/SKILL.md as instructions. The engine needs Python 3.8 or newer. Without Python, the agent applies the methods by hand and says the draft is unverified.

Quick start

python skills/pattern-making/scripts/pattern.py block all --body women --size 38 --out out
python skills/pattern-making/scripts/pattern.py block skirt --measurements me.json --out out
python skills/pattern-making/scripts/pattern.py block bodice --body men --sizes 44,48,52 --out grading
python skills/pattern-making/scripts/pattern.py test

Outputs, inputs in cm and files in mm:

File	Use
pattern.svg	Print at 100 %, check the 10 cm square
pattern_<size>.dxf	CAD software, layers CUT, SEAM, NOTCHES, GRAIN, TEXT
clo3d_<size>.json	CLO3D through clo3d-mcp-extended, curves exact, edges named
clo3d_<size>.py	Standalone script for CLO3D's Script Editor
pieces_<size>.json	Editable pieces, input of the pivot, smooth and piece commands

Layout

skills/pattern-making/
  SKILL.md              entry point read by the agent
  references/           reference analysis, design from sketch, measurements, ease, blocks,
                        transformations, finishes, piece format, CLO3D
  references/techniques/ one sheet per garment family, accessories and sewing techniques
  references/kb/        knowledge base: 570 entries (garments, pieces, techniques), searchable
  examples/             garment specs: notched-lapel jacket (fitted, oversize), velvet coat
  scripts/pattern.py    engine and command line, standard library only
  scripts/garment.py    whole garments from a JSON spec (references/garment-spec.md)
  scripts/sheet.py      PNG pattern sheets (optional, needs Pillow)
.claude-plugin/         Claude Code plugin and marketplace manifests

Notes

• The formulas are proportional and tied to no author. Values from a given method (Aldrich, Armstrong, Müller, Esmod) go through the measurements file.
• A block is a starting point: validate it on a toile before cutting the fabric.
• The CLO3D export was verified live on CLO3D 2025.2.236: each pattern edge becomes one CLO3D line of the same length.

Licence

MIT, see LICENSE. CLO3D is a trademark of CLO Virtual Fashion Inc.; this project is not affiliated with or endorsed by it.