From this line make a mark every inch the full length, then go back and divide making marks every ½ inch, then ¼ inch and 1/8 inch. These lines should be staggered for ease of use. What I am describing is similar to how tapes and rulers are staggered. See Figure B. Write and mark measurements in large dark writing. This will ensure the measurements are clear in photographs.

When writing the numbers in, use decimal points and not the ½, ¼. For photo purposes, there is no need to write in the 1/8-inch numbers. The conversions are:

½ = .5
¼ = .25
¾ = .75

Place a double thickness of tag board under the 3-inch strip so that the sides of the two pieces are at a 90-degree angle to the 3-inch strip. See Figure C. Note that the double thickness is for construction purposes only, and is not used with the caliper. Carefully bend the 3-inch strip at approximately 2-inches from one end over the two thicknesses of tag board.

Hook the bent portion over the 4-inch piece so the 2-inch section is under the 4-inch piece and the 3-inch piece sits at a right angle to the 4-inch piece with the bulk of it over the top of the 4-inch piece to form an L-shape. Carefully mark the 3-inch piece at the edge of the 4-inch piece. See Figure D.