There are two kinds of clay figurines based on the way their shapes are formed: one is formed by joining lumps of clay to the torso to form arms and legs; the other is formed by building clay coils, similar to the pottery-making method, which results in hollow torsos and heads.
1 (p. 160):
A hollow cone-shaped clay figurine was made first, then the head was mounted on top of it.
2 (p. 161):
The largest hollow clay figurine, 41.5 cm in height. The arms and legs are hollow as well. It was excavated in nearly perfect shape with only the hair and arms missing. This was found in a grave site from late Jomon period.