The casings I used for the bigger sausage are made from durable beef collagen which makes stuffing exceptionally easy. The flat collagen casings are non-edible but easy to peel-off the sausages when they are cooked/smoked.
I usually run the smoker around 120-140 degrees for several hours, then finish cooking the meat in the oven till the meat temperature reaches 160 degrees.
Below are sticks made with edible casings....good stuff.