Below was abstracted from a Chinese paper cutting book:
ZHANG Yongzhou (a well known paper cutout artisan) summarized the cutting of lines in 5 words:
circular, sharp, square, deficient and thin.
CIRCULAR – lines must be as round as a full moon
SHARP – as sharp as a fine blade
SQUARE – as square as a brick
DEFICIENT – as deficient as saw-teeth
THIN – as thin as human hair