This is easier and cheaper than it looks. Just go to your fabric store (JoAnn’s Fabrics is where we got this) and ask for a fabric sock. They have bolts of stretchy cotton (t-shirt material) fabric that is like a tunnel. It is a wonderful addition to any kids obstacle course and can be tucked away in the closet when you need to put it away. No sewing or assembly required, just cut how much you want your tunnel length to be and use it.
BTW They have several colors to choose from.
Let the sensory input begin!
Download the PDF for Fabric Sock Tunnel