Extrusion is a reasonably mature technology. The most demanding applications historically lie within the plastics industry in which great advancements have been made and from which pharmaceutical extrusion technology has evolved. Extrusion technology covers a variety of machine types, dies, and an even bigger multitude of materials. One of the most common problems is the mismatch among material, die, and machine. By reviewing some of the techniques in extrusion die design and supplying a few insights, it is possible to design dies to produce quality products. The most common types of annular dies used in medical device applications for tubing are of a relatively simple "spider" type construction. There are basically two aspects to residence time with respect to die design: mechanical and rheological. From a mechanical aspect, the residence time is affected by how well the components that make up the die are machined and polished.