MOLD STYLES =
There are 6 basic mold designs: Regular Size, Mini, High Skate, Intermediate High Skate, Gold Base, and Blue Base. They are made from paper-Mâché: a composition material similar to dry wall cement. Bobbing head dolls have a compression spring glued to the head and attached to the neck post, which allows the heads to bounce up and down. Thus, the term "bobbin', "bobbing", or "bobber". Although they are also called Nodders, technically they are not. The pre 1960's "Nodder" dolls had a pin in the neck area, which would allow the head to nod or pivot forward and backwards.
SPRING INFORMATION =
In regard to the springs, there were 2 different types of compression springs used: COIL WITH STEM & STRAIGHT COIL.
The Regular, High Skate & Intermediate dolls used a unique spring that had 4 large coils (at the head area) with a 1" long stem that attaches to the neck post with 2 small coils.
The Mini, Blue Base & Gold Base dolls used a "STRAIGHT COIL" spring design that had 7 - 10 coils. There is a small and large version of both types to accommodate the different size heads. Most of the odd-ball dolls used the "STEM" type spring.
The Blinking Eye dolls, and the NY Ranger variation (black base decal) used a "STRAIGHT COIL" type spring. See the pictures below for 3 different styles of springs.
COIL WITH STEM DESIGN (fat and narrow variations) STRAIGHT COIL DESIGN