process for packaging items having irregular shape and size , singly on in groups , in a stretchable film of plastic material , comprising the operations of forming , filling and sealing a bag from the stretchable plastic film such film being maintained under adjustable tension and stretch and subsequently adherent on the items due to the elastic &# 34 ; memory &# 34 ; of the released film . the machine for operating the process continuously comprises essentially two members subjected to a reciprocating motion , provided with means for gripping , stretching , sealing and cutting the plastic film , each of such members being subjected to a motion having a stroke of varying length and independent from the one to the other member .