A simple fiber extruder has been developed to produce small diameter filaments of frozen deuterium. The extruder is based on a commercially available liquid‐helium‐cooled cryostat, and only the actual deuterium extruder mechanism must be fabricated. The extruder features interchangeable nozzles and fibers ranging in diameter from 40 to 300 &mgr; have been made. All fibers are over 10 cm in length and their physical dimensions remain unchanged for at least 4 min. The neutral gas density outside the fiber is on the order of 1013and drops off with the inverse of the radius. These fibers are used to provide the plasma for the NRL densez‐pinch experiment whose objective is to study the fusion application of small, dense plasmas.