The unspun silk dope consists of various amino acids, some of which form very long and complex structures. Due to their chemical properties, these amino acids form what are called beta sheets, which are flat, corrugated structures that can be stacked one on top of another. When stacked, they form the crystals, in between which lie loose, amorphous regions that are elastic. The crystalline structure, together with the elastic amorphous regions, give spider silk its mechanical properties.
In order to get a finished product at least as good as natural spider silk, it is not enough merely to extrude the unspun silk dope. Long fiber processing ideally also removes excess water from the fiber, and subjects the forming fiber to shear stress, or a force parallel to the direction of the forming fiber, by forcing it through a hyperbolically tapering tube.
Spider silk can be formed simply by extruding it from a syringe through a hollow needle. However, this does not very closely mimic the process of a spider's glands, and produces a silk with reduced strength. An improvement of this idea is to find a method using microfluidics, a science dealing with the manipulation of fluids on a sub-millimeter scale. This would enable very tight control, but is potentially expensive.
In electrospinning, fluid is held so that it can leave a chamber by capillary action, which induces a fiber shape. A difference in electric potential is induced between the fluid and a substrate below, so that the fluid is attracted to the substrate. Tiny fibers jump almost instantly from the exit point to the substrate. This produces fibers on the nanometer scale, smaller even than the micrometer diameters of natural spider silk.