A method for forming an image sensor is provided. The space is smaller in plan than the substrate. Then the protruding sheets enlarge the hole. The coin scale is adapted to receive at least one group of coins of a single denomination and to determine a coin total for the at least one received group corresponding to the value of the coins in the received group. The sliding member is slidably engaged with the guiding member such that the sliding member may be repositioned between a first position relative to the base member and a second position relative to the base member by being slidably moved across the guiding member which is connected to the base member.