A very kind Mr Sweet mailed me this rather nice bridge casting for the Cornish project last week. I'm sure you'll agree that it is a wonderful piece of work, with nice deep rendering which would be quite tricky to achieve by scratchbuilding.
When it arrived, I expected it to be resin or plaster, but much to my surprise it is fibreglass! The stone being moulded into the gel coat. The joy being that it is very tough and very light - ideal for a portable layout.
The shot above shows it in primer in preparation for dry brushed top coats of various pale greys, beige, browns, creams and so on. Real stone is a fascinating mix of subtle different colours and shades, and certainly nothing like the painting-by-numbers approach often used which feature large blocks of solid colour - that approach suits engines and carriages just fine, but not hacked up materials straight from the ground which will have been exposed to the elements for decades.
I'd be very interested to know more about this stone effect beauty, because fibreglass is not a material we normally associate with toy chuff chuffs, it being more a material of yachts, dingies, kit-cars and the aeroplane industry.