Clay stamps are used to make a repeating image, pattern or texture that is stamped into wet clay (or any soft material that will hold a shape). Most artists who work with clay make their own clay stamps for the convenience of owning a tool that will make the same impression over and over again. Clay stamps also may be used to create a "signature" that can be stamped into the bottom of any pottery piece to identify the artist who made it.
Pull a piece of soft clay from a block of wedged, ready to use clay. Roll this clay into a short column, no thicker than one inch in diameter.
Squash the roll of clay on one end so that it flattens to a wide round surface. This will be the surface of your stamp.
Draw the outline of the image or pattern on the stamp, using a needle tool. Draw the image large enough that you will be able to carve around the exterior of the image, so that the image itself is a positive impression-that is, the image will poke out from the stamp, it will not be an indentation made into the flat surface of the stamp. For example, if you wish to create a stamp of a happy face, you'll want to draw a circle into the centre of the flat surface you just created in step 2.
Carve around the outside of the image you just drew, using a wire loop tool. So in the case of a happy face (if that's what you chose to make), you would carve out all the negative space around the circle you drew in step 3, making the surface of the stamp a raised, flat circle.
Draw any details into the image, using a pointed wooden tool or a needle tool. In the case of the smiley face, you'd poke two holes for the eyes and draw a smile underneath.
Allow the stamp to dry for several days, then fire it at a local art studio with a kiln, if you don't have one of your own. Alternatively, you can create clay stamps out of polymer clay, to be hardened in your oven instead of a kiln.