holes and channels cut through them these plates have substantially planar upstream and downstream surfaces that form substantially regular geometric shapes a stack of two or more of these plates can be used in forming multicomponent fibers or mixed component yarns having various cross sections these plates are inexpensive and disposable and have a high degree of design flexibility the flow holes and channels may be cut through using electro discharge machining edm drilling cutting including laser cutting or stamping preferable machining techniques are those which allow for a wide selection of plate materials so long as the materials do not creep under the spinning conditions and do not adversely react with the polymers possible materials include both ferrous and non ferrous metals ceramics and high temperature thermoplastics the high temperature thermoplastics can even be injection molded while methods for machining eroding stamping injecting etc are readily available in the art for convenience an example of how a plate may be made is provided in example 1 the thin distribution flow plate sets of the present invention include pattern plates and boundary plates unlike other comparable thin distribution plates the disclosed pattern plates have transverse channels cut completely through from the upstream surface to the downstream surface the surface of the next adjacent downstream plate serves as the bottom or boundary of the flow channel therefore each thin plate contains only one feature i e arrangement of channels and holes to distribute melt flow in a predetermined manner greater flexibility relative to other more complicated flow distribution plates is provided referring to fig1 a spin pack assembly constructed in accordance with the present invention and designed to produce sheath core bicomponent fibers of round cross section is illustrated assembly 10 includes the following plates sealingly adjoining each other polymer inlet.