To envision the basic concept. With a square piece of paper.

Fold on its vertical axis to get 33 even elongated rectangles.

Take this strip and fold it to 33 even squares.

Put a pin hole through the center and pass some sewing thread through and leave ample length to allow the flat unfolding of the sheet.

The resultant pattern creates a visual basis for repetition through a 2d plain.

[link to en.wikipedia.org]