So I ran out of Sculpey Firm just as I was about to start head no. 4 I scrounged my stash and found some normal sculpey (which I feel is too soft for small details) and some old Fimo. I decided to use the Fiom and re-constituted it with some isopropyl alcohol and diluent, I shaped a cube around some wire and baked it. This was then carved and sanded down to an oval shape close to the size I wanted the head to be. I then proceeded to sculpt details on top with more unbaked Fimo.