When I had a proper job, we had a note on a drawing that said - Apply a very small amount of petroleum jelly and then wipe it ALL off.
The idea was to get a very thin coating, but that note always amused me...
The Peco wheel cleaner is still a good and cheap device.
Add a couple of croc clips and you're away. Or, even buy two and mount the brushes at a suitable spacing and drop them on the track - there is a contact strip on the back that will collect power from the rails directly.
For non-driven wheels, a brass brush in a cordless multi-tool is a good way.
Radio 4's In Business is covering 3-D printing tonight - http://www.bbc.co.uk/programmes/b01sdrhf - give it an hour or so and it will be available to Listen Again..
It's on live as I type this and they've just interviewed the Shapeways chap...
No problem. He knows what he's doing on rail-related matters - and he can search effectively in Dutch, which may turn up stuff not readily available to us..