es: SELLO AL CUÑO
Seal in the past was used for registering property, letters, etc. Hot wax was put over a small space where the two parts join and stamped with the owner’s trade mark; this sealed the letter and proved it had not been opened.
A seal is now used by potters as a trade mark. It can be made in clay or any other material, have any shape, round, square, etc. and long enough to hold comfortably. At one end the trade mark is modeled in relief or recess and if made in clay it should be fired. This method is only needed if you want a special design, like your initials. If not, you can find a small object with a shape you like and indent it into the clay.