Embodiments provide a process and machine for waterproofing semimanufactured footwear, clothing items, and accessories. Embodiments also provide semimanufactured products obtained with said process and/or machine. The semimanufactured product may have a three-dimensional conformation with an inner surface and an outer surface. A waterproofing sheath may be formed by superimposing two edges of a semi-permeable membrane, and welding the superimposed edges of the semi-permeable membrane to one another to form a strip and to give the waterproofing sheath a three-dimensional conformation. The semimanufactured product and three-dimensional waterproofing sheath may be arranged on a shaped support with an adhesive between the semimanufactured product and the waterproofing sheath. The semimanufactured product and/or waterproofing sheath may be pressed to bond the waterproofing sheath to the surface of the semimanufactured product.