An extruder pushes clay through a shaped die to produce a continuous length of that profile. It makes handles, coils, hollow tubes and decorative strips quickly and identically, which is why production potters have one and occasional makers usually do not.
What it is for
Repeat elements. Twenty mug handles that match, coils of even thickness for building, hollow box sections, and strips for applied decoration. Anything you need many of and identical is what an extruder is for; a single handle is quicker pulled by hand than set up and extruded.
Dies
The die decides the profile, and most extruders come with a starter set and take custom dies cut from sheet material. Hollow dies with an internal former produce tubes, which is how box sections and hollow legs are made. Cutting your own dies is straightforward and is where an extruder becomes genuinely versatile rather than merely fast.
Wall mounted and hand held
Wall-mounted extruders give leverage for stiff clay and larger sections and need a solid wall. Hand-held versions are cheaper and limited to small profiles in soft clay. Match the choice to the work: a wall extruder for handles and structural sections, a hand-held one for decorative strips and small coils.
Clay condition
Extruding needs clay slightly softer than throwing clay and thoroughly wedged, because an air pocket comes through as a hollow in the extrusion and a hard lump jams the barrel. Reclaim that has not been properly prepared is the usual cause of an extruder that seems to need enormous force.
Questions people ask about clay extruder
What is a clay extruder used for?
Making repeat elements: matching handles, even coils, hollow tubes and decorative strips.
Do I need one?
Only for repeat work. A single handle is faster pulled by hand than extruded.
Why is my extruder so hard to push?
Usually clay that is too stiff or unwedged. Extruding wants slightly softer, thoroughly prepared clay.