to make cords (see Molina)
mecachiua. ni. (pret. onimecachiuh) hazer cordeles. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 55r. col. 1. Thanks to Joe Campbell for providing the transcription.
mecatl (cord) + chihua (make)