I know this isn't new to some but I figured I would share my results. This is a roll of reflective tape I got from the local Ace hardware out here. It's very thin and easy to apply. And seeing as my freelanced railway is set in 2009 a necessary addition. As in 2005 the FRA made the usage of conspicuity tape mandatory with all locomotives needing to be at 100% compliance by May 31st 2010. So far I have done one side of my SD35. That is barely crawling along t this point. 
Very easy to apply. Cut the strips 2.35 mm wide by about 10mm long. And apply. I don't worry about being perfectly even. As most tape I have seen applied on the prototype are slightly misaligned. Took me about 10 mins to apply. The thickness isn't noticeable from any normal viewing angles and looks fantastic when it reflects.something I could not get using microscale decal stripes. Hope it gives some ideas to add the tape to your rolling stock as well.
and Yup. That's the tape right there. 
