Hi Eddy
thanks greatly for your comments.
Its easy to describe making the base, it wasn't hard at all, and I've built less than 10 dioramas in my life, so am not really an experienced diorama building expert.
Ionly took one 'in progress' picture, maybe next time I will take more, if it might help someone
Firstly I cut a piece of 2mm thick MDF (Medium Density Fibreboard) to the right size so that it would fit neatly on the pine base I had already made. This MDF is sold in sheets of all sizes at hardware shops and is very easy to cut and use.
Then I placed the KV-1 in various positions till I liked the angle and place. I then used a pencil to trace around that spot, to assist me before spreading wet plaster about .
I then mixed some plaster of paris till it was quite firm, not too sloppy and formed the flat raised area where the figures are standing, then made the road area. Where the ruts are for the tracks is basically on the bare board. I then did a light sprinkle of fine dry dust (gathered from my garden) over the still wet paster. This included tiny bits of dead plant matter, which adds to the effect.
To shape the mounds I used paint brush handles, and to get a random texture used a large 2 inch paint brush pushed and stroked randomly, to give the road area a roughened appearance.
To finish I placed the tank on the ruts in wet plaster to get some track impressions.
When dried, which is only 30 minutes or so later, I painted the whole thing matt black with diluted artists acrylic paint, and ensured all the white areas were covered. Later I dry brushed enamel paint over this, and then more cheap artists acrylics. It took a few coats till I had the brown mixed to the right shade
When that dried I sat the hull (minus the turret) on the road. I then mixed artists acrylic paint (with no water added) which is about the consistency of toothpaste, till it was the right colour then applied it with a brush in the ruts and thickly around the tracks where they make contact with the road, and brushed smaller amounts on the rest of the tracks and roadwheels. I then placed a weight of about 1 kilo on the hull to press it hard down into the acrylic paint until the paint had dried, which was a few hours, and in effect this glued it in place.
The grass is 'Heki' brand grass fibre, sprinkled over diluted white glue (diluted 1/3 glue to 2/3 water)
below picture is during painting of the base, it needed a few more coats to get the right shade, this was early on, and this was before the thick acrylic 'mud' was added, which was last

cheers
Neil