Prepare a non-porous surface on which to roll out your air-hardening clay. I like to use glass or plastic cutting boards.
Roll your clay out to about 4mm or 3/16” thick. Imprint an image on your clay with a rubber or cookie stamp. If necessary, wet both the clay and the cookie stamp with a finger dipped in water to stop them sticking to each other. If your stamp leaves any unwanted wrinkles or tears in your clay then, again, a finger dipped in water can be used to smooth the surface of the clay.
Now position your cookie cutter in the desired location over your stamped image and cut out your ornament.
Soak your ornaments in 10-20 drops of essential oil in a covered bowl (not plastic) until all of the essential oil has been absorbed (if they are a gift, do this as close to the time of gifting as possible).
Hang them on your Christmas tree or place them in a small organza bag and gift to a teacher, friend or relative.
Wet clay can be grey in color, but it will whiten as it dries.