If you can remember back to February then you'll unfortunately be able to recall my first rather poor attempt at modelling cobble stones. In the comments to that post GB also pointed out that a cobbled street is usually paved with irregular stones, whereas setts (which are what I've always called cobble stones) are made from regular, usually rectangular, worked stone. While my approach to modelling cobble stones improved until I was happy enough to produce a small photographic diorama the fact remains that I've been producing regular circular stones which are neither cobbles or setts.
Part of the problem has been that producing regular circular stones using the ink tube from a biro is easy, but I couldn't think of a similar way of producing rectangular stones. Yesterday I realised that I should be able to build a simple stamp from some of the styrene strip I have kicking around. Essentially I built a rectangular tube from some 0.5mm thick styrene (Plastruct #90729) held together with plastic weld from E.M.A. Model Supplies. Once the weld had set I filled down the joins and the styrene to thin it a bit below 0.5mm leaving me with a stamp I could use to make rectangular stones of approximately 3mm by 1mm which represent 9 inch by 3 inch given that I'm working at a scale of 4mm to the foot.
Armed with my stamp I produced another small test piece using DAS clay as before, which was then painted in the same fashion as my previous attempts.
I think these setts look really good, although those between the rails (which is where I started) could be better; not sure if I should put them in the other orientation to those outside the rails, or just not offset each row as two bricks (i.e. 6mm plus the gaps) are a good fit between the rails? So now I have a decision to make, cobbles or setts? I think the setts are more realistic as the cobbles are too uniform, but let me know which you prefer in the comments.