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.
An initial marker for bags can be made of a beet or potato. Cut off enough of the vegetable to provide a flat surface of sufficient size and then cut out the letter as shown in the sketch, and use shoe blacking as ink. In cutting, remember that most of the letters must be made reversed in order to print right. For example, in making a B, draw it out on paper and cut it out, then lay the face of the pattern on the flat surface of the vegetable and cut around it.