Both types can be fermented by the addition of a lactic acid producing bacteria culture that provides a wonderful tang to the sausage in addition to the enhancement of long keeping qualities. Sausages are made from ground meat. This can be purchased from a butcher already ground but the true sausage buff will sooner or later want his own meat grinder. These can be inexpensive hand cranked affairs found in most kitchen junk drawers or motor driven grinders running a wide range of prices. I use the inexpensive attachment sold for use with the Kitchen Aid mixer.
All grinders operate on the same principal.
An auger pushes the meat into a rotating blade that chops the meat as it forces it through the the stationary output plate. The size of the holes in the plate determine the coarseness of the ground meat. Real sausages are stuffed into casings and this requires a stuffer . Fortunately, this can be done with the same meat grinder by adding a stuffing tube. The choices are myriad and include natural animal parts, fiber and plastics.