I have a plastic tube that has a wall thickness of around 3 to 4 mm and it is transparent. I am trying to build a ring for the top of the cylinder that just illuminates the sides of the tube, but nothing inside of the tube.
For more context, I am trying to light up the sides of the tube as shown below. I don't want the rat inside to be illuminated by the light as much as the sides of the tube will be illuminated.
I'm thinking of using LED light pins, but I am unsure of whether that will just illuminate the side of the tube or the whole thing. Any help?