For just a bit of fun Jill you could make your own tube runs out of cardboard or plastic film and tape with holes punched in them. Make the sections not too long so that if he decides to stop in one it is easy to detach and then get him out. Use strips of velcro to hold the sections together. A nice crafty idea for the weekend.
We use the big card rolls out of christmas paper which are nice and wide and plastic film from clear file folders as long as it is strong. You can make wire mesh sections too.