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