>>6390977For the original (which you can mold and recast), start first by getting some plasticine clay and making the basic dimensions of the head with extra mass. Next, mold and recast using KwikWood epoxy putty (use either a light dusting of talcum/baby powder in the mold prior to the Kwikwood). Let harden for 2hrs, remove, then let fully-cure for 36-48hrs (depends on humidity of where you live). Fully cured Kwikwood will be bone-dry, meaning sanding or scraping an x-acto blade across its surface will produce a fine powder easily. Begin carving with an x-acto knife (get plenty of spare blades), chiseling out impressions and sanding with medium to superfine grit depending on the finish desired. Once fully carved, lightly dust with talcum powder and make a new mold of the complete face, recasting in your choice of epoxy, resin, etc.
Kwikwood can be found at Walmart and home improvement stores in the adhesives or paint aisles.
For an epoxy that mimicks soft pvc, look for KwikPlastic epoxy putty. More crumbly than real plastic, but has some flex and roughly the same working and gardening time as Kwikwood)minus the 36/48hr bone-drying).