If your Super Sculpey Firm or Super Sculpey Living Doll Polymer Clay(or any other polymer clay) is ok, but too firm and needs just a bit of softening:
Add a bit of Sculpey Smoothing Oil, knead.
The clay restores to perfect, like new, texture.
Put in plastic bag
Add a few drops of Sculpey Smoothing Oil
Close the bag and shake vigorously
Leave overnight (or for a few days)
Knead in small batches in front of TV.
Still work, but much more satisfying.
The clay restores to perfect texture, almost like new – depending on your diligence in mixing effort.