A method for forming a three-dimensional objects by photo-curing a photo-curing liquid polymer through exposure to a radiation, said method comprising: progressively curing layers of said photo-curing liquid polymer, in the space between a sheet transparent to said radiation and a supporting plate on which already-formed portions of said objects adhere so as to form said three-dimensional objects 18) by growth in a layer-wise fashion, said transparent sheet defining a bottom of a tank, and progressively moving said supporting plate away from said transparent sheet as said three-dimensional objects are formed, on a side of said transparent sheet facing towards said photo-curing liquid polymer a membrane is disposed, said membrane being transparent to said radiation and said membrane being covered by a layer of liquid lubricant which is released gradually by said membrane, said membrane being made of a self-lubricating polymer, i.e. a polymer inside of which there is a liquid lubricant, said membrane being displaceable with respect to an area in which said photo-curing liquid polymer is undergoing curing by said radiation thereby resulting in said growth; and during said growth, at times when said supporting plate is raised vertically away from said transparent sheet, laterally displacing a layer of liquid lubricant disposed between the transparent sheet and the photo-curing liquid polymer with respect to said area of said photo-curing liquid polymer undergoing progressive curing by said radiation, by means of laterally displacing said membrane with respect to said area of said photo-curing liquid polymer undergoing progressive curing by said radiation, through dispensing of said membrane from a first reel and taking up said membrane on a second reel, said first and second reels disposed on opposite sides of said tank in which said photo-curing liquid polymer is undergoing curing. progressively curing layers of said photo-curing liquid polymer, in the space between a sheet transparent to said radiation and a supporting plate on which already-formed portions of said objects adhere so as to form said three-dimensional objects 18) by growth in a layer-wise fashion, said transparent sheet defining a bottom of a tank, and progressively moving said supporting plate away from said transparent sheet as said three-dimensional objects are formed, on a side of said transparent sheet facing towards said photo-curing liquid polymer a membrane is disposed, said membrane being transparent to said radiation and said membrane being covered by a layer of liquid lubricant which is released gradually by said membrane, said membrane being made of a self-lubricating polymer, i.e. a polymer inside of which there is a liquid lubricant, said membrane being displaceable with respect to an area in which said photo-curing liquid polymer is undergoing curing by said radiation thereby resulting in said growth; and during said growth, at times when said supporting plate is raised vertically away from said transparent sheet, laterally displacing a layer of liquid lubricant disposed between the transparent sheet and the photo-curing liquid polymer with respect to said area of said photo-curing liquid polymer undergoing progressive curing by said radiation, by means of laterally displacing said membrane with respect to said area of said photo-curing liquid polymer undergoing progressive curing by said radiation, through dispensing of said membrane from a first reel and taking up said membrane on a second reel, said first and second reels disposed on opposite sides of said tank in which said photo-curing liquid polymer is undergoing curing.