Hi Michele,

A cylinder 2 pipe is a rotationally symmetric surface, and coatings cannot be applied to this surface unless it is set to a Mirror material. I think you can use 'Cylinder Volume 2' object instead. This object is very similar to the cylinder 2 pipe, except the front and rear faces are included to make the shape a closed volume. Because the object is a closed volume, it may be reflective, refractive, or absorbing. 

Then, you can make a cylinder light pipe by using two cylinder volumes and performing a Boolean operation on them (I'm attaching a dummy file here for your reference). Once you create Boolean Native object that represents the cylinder shell, the coating will still need to be applied to the proper face of the Parent object. In order to figure out which face of which parent object to apply the coating to, you can open an Object Viewer by clicking the “View Current Object” button in the Non-Sequential Component Editor.

Best,

Berta