than vertically downward into the passage 125 a solid right cylindrical plug p is inserted into the passage 125 such that its upper end is flush with the shelf 124 accordingly the wafer 130 is disposed in the recess 120 substantially fully supported along its bottom surface against further downward vertical movement as shown in fig1 the ram 131 is then moved downward again against the wafer 130 causing the wafer to bulge laterally outward against the downturned wall 119 this action distends the wall 119 into a substantially contiguous or mating relation with the sidewall 123 thereby making a dovetail interlock when the interlock is complete as illustrated in fig1 the ram pressure is released the wafer reverts back to its original shape for easy removal from the recess 120 thereafter the spring 111 is positioned in the inner housing half 106 and the outer housing half 105 is fitted thereon to form the encapsulated spring housing in the manner heretofore described with reference to fig1 13 the present invention further provides for an interlocked spring punch and stripper assembly 200 of an encapsulated spring housing 201 and stripper guide 202 for use in a punch press assembly such as shown in fig1 wherein a portion of the spring housing is integrally formed on the stripper guide the stripper guide 202 is in the form of a generally cylindrical hollow stem adapted to be mounted for reciprocation in a punch press holder the spring housing is formed with outer 203 and inner 204 tube shaped.