How much time? Original sculpey cures best at 15 minutes for every 1/4 inch (6mm) thickness of uncured polymer. If you need to build up thick areas use several thinner layers and bake for each layer. Apply a thin layer of liquid clay to the baked surface so that the new layer sticks to the older one.
What temperature's best? 275F (130C)
Number of Colors: 2
Package Sizes: This Polyform clay comes in three different sizes. And compared to their other clays, the packages are all jumbo sized. The sizes are: 1.75 pounds, 8 pounds and 24 pounds.
There's always been this part of me that wants to buy the largest pack of white and make a custom dog house (dogaloo?) with the whole thing. Of course I'd have to have a REALLY large oven...
What Does It Cost? This is probably the least expensive polyclay. At 40 cents an ounce or less you can afford to buy plenty for the kids' projects. Check this Original Sculpey link for current prices.
Tips and Hints
The Good: Many school teachers use this for kids crafts because its inexpensive and easy to shape and form. The terra cotta actually feels a bit like pottery after curing. And it takes acrylic paints very well.
Not so good: This type is brittle after baking. Thin areas can break easily. If you want to create delicate, protruding details like a cat's ears, you might choose another Polyform polymer clay like Super Sculpey (a doll maker's favorite), Sculpey III or Premo. There's a chart here which might help you choose a better type for your project.