Thanks everyone.
Cool node Karsten!

The quarter circle version of the Truchet tile pattern will make a good CNC wood carving project.
A few years ago I was unable to figure out the pattern, seen on a TV show, (as it is pseudo-random.)

https://en.wikipedia.org/wiki/Truchet_tiles

The code for Truchet tiles is simple modular arithmetic for random index of 2 or 4 patterns.
http://jean-paul.davalan.pagesperso-orange.fr/divers/truchet/truc.html

The 2D geometry for a set of 4 tiles can be located in Top View in quadrant 3.
Different sets of tiles may be created, curved fat line, duotone, etc.
The program will need to select, by index, the appropriate tile, and place a copy in quadrant 1, to create the row/column pattern.

So create the 4 geometric tiles, name them, and place the names in an array.
Select by Index the name of one tile, and copy the geometry.
The lower left hand corner point should work for copying to row/column.

PDF will be exported to Aspire, for routering.

- Brian