Hi Chaps - many thanks for the kind comments.
The pump and hose were lifted off the 16mm tank wagon I did a while ago - although the pump was only bought a year or so ago. The hose on this, as on Welsh Ernie, is made from resin core solder - it can be bent to the required shape easily, and retains the shape when you've finished. It just needs some paint to finish it off.
The paint effects are a bit experimental - started with Pretty Flat. In each case I started by spraying the chassis with matt black from a rattle can. Then I made up a thin mix of rust colour, and painted it quite roughly on one surface at a time, immediately wiping most of it off with some kitchen roll. You have to be careful that you catch any drips on other surfaces, as once they dry you can't get them off! Then I repeat, wiping again, to build up very thin rust colour. I use the ball of my thumb to wipe around raised detail, so that more of the thin wash is left around things like rivet heads.
Once the washes are dry I use a graphite stick from the local art shop to get the metallic sheen. I rub it on the edges and raised details to produce highlights, and on flat surfaces I rub the edge of the stick gently over and then rub it with my thumb to spread the graphite thinly and evenly. The finished effect depends on how many times you do the wash and how much graphite you put on. After my '20 years underwater' rust on my skips, I'm trying for more subtle effects!
I used the thin wash on the oil drum, too - thinned Weathered Black from the Railmatch paints. The drum was sprayed with Railmatch green, which is semi-gloss. The thinned wash won't stick at first, but I put plenty on, then used a big piece of kitchen roll rubbed all round, and the paint residue stuck, and formed a surface that will take subsequent washes. The wash dulled down the gloss a bit, and built up round the raised bands to make a bit of grime.
I guess you need to try it out and see what more washes or more graphite turn out like - the big problem is stopping just before you've done too much!