Tia: I know my project was a bit different as I crocheted the snake I made for my grandson, but I believe I can help. If your knit is very stretchy, your idea to line it is a good one. Just cut the non-stretchy fabric the same as the stretchy and sew the snake together as if the two were one piece of material. I don't think the fusible backing would work as well. Because it is not woven, over time it will separate and your snake may develop "hernias". Whether or not you add a curve depends on a couple of things. Are they going to be purely decoration, or will the grandchildren be playing with them? If they will just lie on a bed, a curve will be fine. If they will be played with (my grandson loves to wrap his around his neck and body) I would not put a curve in it. Also, how densely you stuff the snake will make a difference. If it is going to be played with you might not want to pack it as much so that it can be formed as the child wants. For show only, you might want to pack it a little tighter. Or, again, if you pack it loosely you can lay it in any position you wish. I think just stuffing it with poly fill would be best. Not only would the rice attract bugs and mice; eventually it will settle in the bottom. And if you use the little styrofoam pellets and a hole develops, not only is it a mess, but it can be dangerous for young children.

Mary Ann, I think making the snake straight would make it more fun to play with as they could coil it up or wear it around their neck as Donna said. I would definitely either line it or use a fusable liner on the fabric. If the kids are going to play with it, I would suggest stuffing it with something washable.

Sounds like lots of fun!