I am trying to build a series of tubes for my pet rat to run around the apartment in. But I need for the tubes to be at least 3'' in diameter, preferably 4'' and I need them to be clear so I can find the rat when I need to. The pipes can be flexible or rigid, and I don't particularly care what material they are made out of so long as it is non-toxic. Also, the tubes do not have to be perfectly clear. As long as I can find her when I need to.
Thus far, the best thing I can find is this: