inspiration behind the layout shows the rails in concrete I think cobbles will look a lot better, certainly if I want to portray an early mill scene as well as a modern day museum. To that end I'm doing a little experimenting, like I did with ballasting for Jerusalem, to figure out exactly how I'm going to produce the cobbled surface. The photo shows the current state of my first attempt at laying cobbles.
I'm taking the approach suggested by Chris Nevard, which is to use DAS clay for the surface and to imprint the cobbles using a biro with the nib removed. I'm actually using the inner ink holding tube from a bic biro to give me round cobbles which are 2mm across, i.e. 6 inch cobbles at 4mm to the foot. This seems to have worked well, although I need to be a little more careful about not overlapping the cobbles -- I want random cobbles not crazy paving!
As well as making the cobbles the clay needs to be left clear of the insides of the rails to allow the wheels to run freely. I'm not quite sure what the scale distance for this gap should be, but I used an off cut of rail (the same as you can see in the photo), turned upside down, which I ran along the inside of each rail. This nicely clears out a gap the same with as the rails, which seems a decent starting point. Given that, as yet, I don't have any OO9 rolling stock, I've had to test the clearance using an N gauge wagon (while N gauge is 2mm to the foot it also runs on 9mm track) to test the clearance, and this hasn't highlighted any problems. If anyone has any suggestions on a better way of making the gap, or knows what it should be, please do leave me a comment.
The next step will be to paint the cobbles. My intention is to continue to copy Chris Nevard, and to spray the surface black (Humbrol Matt Black, as that's what I've got to hand) and then to dry brush with a mix of grey and cream and I'll let you know how that goes.