The faces of the apparatus can be so shaped that {TAIL ~ the cross section} of {HEAD ~ the mass} being compressed is urged toward a shape other than that of a regular polygon 
The faces of the apparatus can be so shaped that { TAIL ~ the cross section } of { HEAD ~ the mass } being compressed is urged toward a shape other than that of a regular polygon
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH