I've had these for years and only used them once on a USA Trains 1:29 GP-9, which worked quite well. Decided to try them out on a couple cheap "volunteer" freight cars before attempting locomotives or more expensive cars. I have Bar Mills powders and Pan Pastels. For some reason, the IC gondola looks awful in pics but quite good to my eye on the layout. Maybe it's the lighting. I'm a lot happier with the ATSF boxcar results. In pics at least.
I especially like the way the rust areas turned out on the boxcar. I'm hesitant to try them on my expensive brass, but I did a Bachmann connie that turned out well. I usually stick with airbrushing when it come to steam, but I'd like to try some different effects with the powders.