Rebalanced greys. I used the same curved wall symbol to line the channel as well as the outer walls.

I got distracted and did the background rock instead of getting on with the walls. The only trouble is that there's now a general mismatch in the greys, but we can fix that.

On the progress front, I'm still working on the outer walls of the sewer. I think a nice rugged stone fill would be better on the outside of everything fading into the black, but that's for later.

These wall segments (when I've got them right) can be used at any width and will probably be a connecting symbol in the imperial style.

And this is without the Blend Mode effect for those who want their water murky.

And for those who want it like slime just turn off the EFIs at the end of the list.

Thanks for the suggestions, everyone :)

Actually, Quenten... They might have been adjusted a little since this composite screen shot was made just after the last image in this thread, but....

Well, today's progress is quite un-pretty compared to that, but this is a sewer after all.

Much more work to do to make things look solid and real, and I'm not really sure about the paving slabs either side of the channel.