along the inner walls 103 a and 102 a respectively these lines sl 1 and sl 2 represent the exact area and location for placement and affixation of a stud such as 11 12 or 13 as shown in fig5 and 14 and 15 as shown in fig5 a after the first lines sl 1 and sl 2 are drawn the apparatus is then moved to subsequent marked positions m 2 and m 3 etc along the length of the plank 10 b each of the rib members 102 and 103 have a width w each of which preferably is 1 5 inches furthermore the width or distance wi between the inner wall 102 a and inner wall 103 a is preferably 1 5 inches thus these three widths must correspond to the desired stud depth for the planks 10 a and 10 b as shown in fig2 a and 3b when it is desired to mark the planks 10 a and 10 b using the apparatus 100 of the present invention the planks 10 a 10 b are placed side by side as shown in fig3 a one end mt 1 of a measuring tape mt is placed at an end of one of the plates such as lower plate 10 b and a marker m is used to place a mark at pre determined intervals such as every 16 u2033 along the length of the plank 10 b to provide reference marks m 1 m 2.