PURPOSE: To embody a closed cellular structure by forming a single cell by laser beam pulse groups, of which the respective groups include ≥2 consecutive spaced pulses.

CONSTITUTION: At the time of engraving a series of the consecutive cells on a solid surface by impinging the pulse laser beam upon the same under relative motion, the single cell 6 is formed by the laser beam pulse groups, of which the respective groups include the ≥2 consecutive spaced pulses. As a result, the adjacent cells 6 of the liquid transfer article are eventually equidistantly parted and the uniform cellular structure substantially closed by build-up parts 12 may be embodied.