Additionally, you don't want the Sculpey to be "hard" after it's baked, but still just a tiny bit flexible. It cuts much better with the NWSL Chopper that way.
This worked pretty well for me, but making the new extrusion plates was a PITA, so I went to Michael's and looked for extruders specifically designed for plasticene. Sure enough, they had some, so I got the biggest one, which had some blank plates (which are circular) and made the shapes for my tables, end tables, supports and smaller seat and chairs easily using the small, thin blank plates.