Ask your local butcher for sausage skins - most butchers will be happy to provide these for sale.
Use pig/hog skin on the large nozzle and sheep/lamb skin on the small nozzle. Or, instead of using skin, roll the extruded sausages in breadcrumbs or seasoned flour before cooking.
If you're using skin, soak it in cold water for 30 minutes first, then open it up with a jet of water.
Put your chosen nozzle under a running tap and pull the skin onto the nozzle. Recipes can be found on our website.