significantly spaced from roll 62 it will be appreciated that pressing station 71 may be spaced from roll 62 by a distance of only a few centimeters when foil 63 is very thin to avoid the formation of creases or wrinkles in the unsupported foil portion controller 61 is used to control the operation of motor 67 prior to a sheet forming operation an operator enters desired dimensions of the sheet via keyboard 68 or any other suitable input device entered information or information related to the sheet forming operation is displayable on screen 72 controller 61 is operable to convert the operational speed of motor 67 into a longitudinal feed speed of foil 63 at or downstream from pressing station 71 depending on the thickness and type of material being fed a predetermined length of the free end of the foil at a given station may therefore be derived from the feed speed of the foil accordingly the various steps of a sheet forming operation may be synchronized by controller 61 in response to the number of revolutions of motor 67 following unwinding of roll 62 during a sheet forming operation controller 61 may adjust the speed of motor 67 to.