This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
A large number of coupons had to be marked, and having no suitable rubber stamp at hand, I selected a cork with a smooth end and cut the initials in it. I found that it worked as well, not to say better, than a rubber stamp. An ordinary rubber-stamp pad was used for inking. Angular letters will cut better than curved ones, as the cork quickly dulls the edge of any cutting tool. - Contributed by James M. Kane, Doylestown, Pa.
Ill: Initials Cut in a Cork Served the Purpose in the Absence of a Rubber Stamp