a thermoshrinking tunnel oven for making thermoshrinking plastic material film packages comprises a bottom plate and a top plate having openings for allowing thermoshrinking hot air to pass therethrough , the cross - sections of the openings being controlled by perforated sliders which are independently slidably mounted on the plates . with respect to conventional tunnel ovens , the inventive tunnel oven and method have the advantage that they provide thermoshrinking material packages of even aspect and devoid of unevennesses .