We all know about this staple of modeling. Bruce is very happy with Faller Expert. It comes in a very easy to use bottle.
When we cut off a light pipe in a loco, we don't spend a lot of time polishing the end. A drop of Faller Expert on the end and you get a nice optical surface!
If you don't clear the throat of the bottle, the cement will dry in place and plug up the snout. Not fun! I like to use a piece of 0.015 phosphor bronze wire (Titchy Train Group) as a plug. Just insert it so that the wire runs through the entire snout and no more plugged snout.
Bruce's other Styrene Cement choice is MEK (Methyl Ethyl Keytone), which he buys at the home improvement or hardware store or online. It is very fast to set up and very strong as a complete styrene welder. USE WITH ADEQUATE VENTILATION! It is a minor health risk and, as such, is getting harder to find, expecially in California.