footbeds that are deformable , resilient , capable of exerting a massaging effect on the human foot sole and useful in various kinds of footwear have an upper sole configurated in the form of a continuous pattern of undulating waves produced by the action of a machine that is constructed with two identical rollers positioned one above the other and each covered with closely spaced , evenly aligned , rounded steel protrusions extending around its entire periphery , said rollers being adapted to rotate in countercurrent directions to move a foamed plastic mass of eva polymer forward from a point at which said mass is fed between them and knife means positioned just behind and between the two rollers , which knife means acts to rapidly slice longitudinally into two separate sheets each plastic mass immediately as it begins emerging from between the rollers . the combined action of the counter currently rotating rollers exerts a pressure in order of about 1200 kg per sq . cm . on the plastic mass as it is moved between them . of the two sheets of eva plastic foam that emerge from the knife means the upper one has the waves pattern on its bottom side and the lower has the waves pattern on its upper side . the sheets are allowed to rest and conventionally cut into matching sized pairs of footbeds .