Complex sentence: The basic clay shapes were thrown on the wheel and perhaps refined on the lathe or were assembled from shaped slabs of clay, mold-shaped sculptural decoration was applied to give relief masks, festoons, and the like.
Split into simpler sentences: The basic clay shapes were thrown on the wheel and perhaps refined on the lathe or were assembled from shaped slabs of clay. Mould-shaped sculptural decoration was applied to make relief masks, festoons, and the like.