Abstract: A method and apparatus are disclosed for forming a plurality of impressions (100) in a target surface (101). The method includes the steps of urging a roller element (110) arranged to rotate about a longitudinal axis (L) in a direction of advancement (A) over a target surface, an angle between the direction of advancement and the longitudinal axis is between 89° and 30°. The method also includes the step of as the roller element rotates, forming successive impressions in the target surface via at least one tooth element (113) extending outwardly at a respective region of an outer surface (112) of the roller element.