A nice quick project - a little slate wagon from the RT Models kit in 4mm scale.
The "kit" is simple enough. A whitemetal body and chassis plus couple of n gauge axles. These are glue on to the bottom of the casting with superglue and the job is done. In an effort to make things a bit proper, I files grooves for the axles but managed to get these a bit less than level which meant a bit of fiddling to get the model to sit properly.
If you wanted a working model I suspect some brass tube around the axles stuck in place would do the job. I think this is meant as a scenic accessory though. The real thing would have been worked by a man pushing it along and if you can figure out how to make one of these in 4mm, then you don't need my advice on rotating axles !
Paint is rust washed over with track colour. I will play around with this a bit more to see if I can get a bit more wear and tear to show through.
Eventually this will be "dumped" behind a shed on the box layout I think. With some nice long grass around it I think it will look the business.