I want to try my hand at snack stix. Do you need to use a casing if you extrude the ground meat from a jerky gun onto a grate?
You don't need casings. Disco just recently posted this and it looks great.
You might also want to look at these two caseless snack stick projects.
I've done them casing less with a jerky gun and they come out fine. Take a look at http://www.smokingmeatforums.com/t/148034/another-way-to-make-casingless-beef-snack-sticks#post_1051237 for details and photos.