This may be more expensive than the extruders you have to push down manually, but it is definitely the one for people like me who struggle with getting lids off jars. It is really easy to use, you get a good, smooth extrusion of clay with no effort whatsoever, and with 20 different discs, the range of extruded shapes is great. I would have preferred the half circle to be slightly smaller, but that is a really minor gripe. If you want a professional finish, this is ideal, though obviously, as with all extruders, the clay comes out matt.
I really like this product, it has given me loads of ideas for making stuff, and it is well worth the price.