Based on Celtic Art: The Methods of Construction ¹, which covers how to create Celtic-style knot work this code automates the initial steps for basic knots.

Very briefly, the method is to:

1. construct a single line that is the path of the knot
2. expand to a ribbon around the center line
3. remove the center line
4. interleave the crossings
5. elaboration and decoration

Using this code you will be able to generate up to stage 3 that can be printed and traced.

To make this concrete, the initial step is to generate the path of the knot, shown here including the control points used for path and indicating the unit cell that was mirrored to make the complete knot.

Dropping the construction marks and showing the center line gives

and removing the center line gives

At this stage, this is ready to be printed to begin the manual process of interleaving the crossings. Pick any crossing and decide which direction will be "over". You then move either direction along the ribbon alternating over/under until you return to the starting point.

pixi run scratch

and then edit scripts/scratch.py to your liking.

This project is typed and has ruff formatting and linting applied.

There are no tests other than looking at the demo section of the docs.

The docs can be rebuilt via:

pixi run build_docs

Contributions are welcome, particularly additional knots in demos.py.