is constructed of five plates front face plate 63 rear face plate 64 side plates 65 and bottom plate 66 suitably fastened or bonded together the front and rear face plates 63 64 are machined or otherwise formatted as will be described below with key holes 60 to receive holder assemblies for the reinforcing fibers which comprise front and rear tension tubes front and rear tension tube caps serrated discs and a front tension tube threaded nut referring to fig6 b an edge view of front face plate 63 and fig6 c a plan view of front face plate 63 the inside face 67 of plate 63 contains a circular recess 68 with associated slots 69 recess 68 adjoins a larger recess 70 that extends to the outside face 71 of front face plate 63 recess 70 includes associated slots 72 the axis between slots 72 is perpendicular to the axis between slots 69 a smaller diameter recess stop 73 separates recess 68 from recess 70 rear face plate 64 is similarly configured referring now also to fig6 d g the mold is assembled for use as follows a disc 75 fig6 d having serrated slots 76 is threaded with polymer fibers 88 which are distributed throughout the serrated slots the distribution of the fibers is spatially maintained by the serrations referring also to fig6 g discs 75 with fibers in place are mounted in recesses 68 in the front and rear face plates 63 64 of the assembled mold orientation of discs 75 is maintained by vanes 77 on the sides of the discs which fit into slots 69 alternatively discs.