Materials needed:
Cardboard box
Razor Knife
Ruler or Square
Pencil
STEP 1 Place your straight edge along your cardboard seam and edge and use your marker to make a line. Make two outlines.
STEP 2 Use your cardboard cutter to cut out the two right angle forms. Now you have two arms of a caliper.
STEP 3 Attach them together with a paper clip.
STEP 4 Hold your cardboard caliper over the area to be measured so that the points of the caliper barely touch the subject.
STEP 5 Measure between the arms of the caliper.
