Method for obtaining a plantar image using means for securing and tightening an elastic membrane, as well as to the double-sided machining of the obtained insole, said means taking the form of two adjustable horizontal bars positioned on a scanner or a plurality of cameras and an anti-reflective lens, wherein a membrane is positioned between said horizontal bars and secured using T-flat bars; the stress of the membrane being adjusted using a handle; the foot is positioned on the membrane; an image is taken; and the insole is subjected to double-sided machining on the basis of the image of the surface provided in STL format, with the aid of a securing device that enables the pieces to be rotated up to 180°.The device used includes a plurality of supporting bars with two adjustable horizontal bars, wherein the elastic membrane is adjusted and tightened using T-flat bars and a handle.