A roll of blue-tinted mylar film? http://www.amazon.com/Reflective-My...TF8&qid=1414349494&sr=8-1&keywords=mylar+roll
Roll it out, and shape it to look like a stream. Crumpled up a bit, so it looks like water is flowing? Shouldn't look too bad at night, especially with the right lighting.
Edit: As an alternative, I suppose that even aluminum foil (shiny side up) might work as well, especially with some blue lighting.
Roll it out, and shape it to look like a stream. Crumpled up a bit, so it looks like water is flowing? Shouldn't look too bad at night, especially with the right lighting.
Edit: As an alternative, I suppose that even aluminum foil (shiny side up) might work as well, especially with some blue lighting.