Thanks everyone for all your great comments.
My grandson hasn't seen the model yet, but he has informed me he would like it mounted on a small diorama base, so that's what I've done.
I added a bit of weathering and exhaust blacking, then modelled the tank out of the shallows and running up through the scrub on the beach.
The base is scrap polystyrene. The sand is just that - sand! The scrub is stuff from my garden.
The silicone sea is a sort of flat 'suhshoosh' rather than a big scudumph!, with the water filling the tank tracks in the sand. I didn't want to hide the crazy colours on the tracks, so I've kept the sand off them.
Here's the pictures.....
Flattened silicone, then worked with a nail.
.......not such a wacky pattern as it looked!
For the Grandson's shelf - I hope! I don't use picture frame surrounds for this kind of subject. Preferring to leave it sort of 'rustic'.
Cheers all, and thanks for looking.
Ron