① Drop nail polish of your choice on a container filled with water
② Trace with a bamboo stick as if cutting the pattern vertically
③ Sink the clear smartphone case into the pattern to transfer the marble pattern
④ Apply a top coat

(POINT)
・ When dropping nail polish, drop it while moving it to the left or right

(Items used)
・ Clear smartphone case
・ Manicure
・water
・ Bamboo stick * or toothpick