OK a bit of a quick and dirty SBS, but hopefully it will make my previous explanation a bit clearer.
Step 1 & 2
Didn't have any MDF so just used a piece of scrap wood, coated with PVA which was left to dry. When dry modelling clay was pressed onto the surface - the clay will reactivate the glue and help it stick to the wood.
I rolled out the clay basically level, however as I was trying to show a cobbled road I made the clay thicker at the crown of the road ......... and where the gutter was planed to be I hollowed out the clay with the back of a spoon. You may just be able to see these effects on the r/hand picture above.
These are the tools I use for impressing the cobbles/setts ... hopefully you can see I have tapered /sharpened the edges.
MPH ... this was what I was trying to explain, the left hand picture is what not to do each cobble pressed in individually and apart! Right hand picture shows what mean , the tool is over laid into the previous impression.
All the impressing done , you can see where some of the individual setts have lifted and also where I have not been accurate enough in placing the tool ... as per Step 4!
After a minute in the Microwave, hopefully you can see where the clay has started to dry out ....... it also shows I was rushing. Should have let the clay dry out for an hour or so naturally and then used shorter burst in the Microwave. Because I have overheated it there is some rippling of the cobbles due to steam being produced under the clay, this overheating has also led to some unnatural shrinkage leading to some cracking along the joint lines
Gives a sense of scale, also shows some of the shrinking mentioned above. I have started to brush the clay with a stiff brush to clean any debris and to round some of the cobble edges.
A bit more care with the clean up,then some painting and finally infilling of the joint lines .... but you all know how to do that so will shut-up now, hope it helps. ( took about 90 minutes to do .. including glue drying time)
After a couple of hours, I have given them another brush ,cleaned up some of the joint lines and although not coloured yet I have brushed in some fine sand (chinchilla dust) just to give an impression of what it could look like.
In real life it was usual to fill in the joint with a pitch/bitumen mix .......... anybody got any bright ideas how I should do that .... I was wondering about black tile grout after the setts have been painted and sealed