SAUSAGE MAKING EQUIPMENT
Various different ones on the market, from very cheap ones to quite expensive robust professional ones. The ones below use sausage stuffer attachments that are an optional extra I bought to go with my Mixer, turning the mixer into a sausage machine. The sausage stuffer comes in 2 separate funnels, one thick and one thin for taking thick & thin casings respectively.
MIXER, GRINDER, FOOD TRAY & SAUSAGE ATTACHMENTS
This sausage stuffer requires the mixer and its grinder attachment in order to make sausages, & Food Tray attachment highly recommended.
Collagen Sausage Casings
Left does thin sausages, and right, thick sausage. They go over the thin or thick funnel respectively. The butcher from whom I bought these from said these are natural casings, not synthetic, & sausage making book I read pointed the same. These have the advantage of being stored in the pantry as long as they're dry.
Though I haven't tried them yet, there's also natural hog casings which are quite different to use and store.
Both these types of casings are available online (see Online Stores topic & other websites).