Medical implant preform produced using an inside out flipping method

A method of making a medical implant, comprising:

• (a) using a polymer solution to form a preform with a desired thickness around the surface of a mandrel, wherein the mandrel has a plurality of three-dimensional convex shapes, wherein the formed preform distinguishes an inner surface and an outer surface;
• (b) removing the formed preform from the mandrel;
• and
• (c) flipping the formed preform inside-out resulting in the inner surface of the formed preform becoming the outer surface of the inside-out flipped preform, and the outer surface of the formed preform becoming the inner surface of the inside-out flipped preform, wherein at least part of the inside-out flipped preform forms the medical implant with a plurality of three-dimensional concave shapes;
• (d) maintaining the concave shapes of the plurality of three-dimensional concave shapes as the medical implant.