You can find the Walls HERE and the Roofs HERE and HERE.
Using the terrain roofs is not hard, though it can be a bit confusing at
first. Like the invisible fence, there are "dots" to show you the
exact space that the roof will actually be sitting on.
To make your own "cave" using any of the walls I've released, follow the
Place 3 walls, like you're building a house:
Add terrain roof. The walls make it easy to see that you're placing it
in the right place:
If desired, add foliage, rocks and/or a small shelter:
Only the center square will be inaccessible for you to place on, as that
is where the roof's footprint is. Animals, however, can walk right
through that space!:
Now, you can leave it, as-is, or you can hide the area.
The same methods can be used underwater. I've included an example with
the ztds that show how it looks.
You can use multiple roofs to create interestingly-shaped hidden areas,
and under these larger areas, you CAN fit a large cave shelter if you
place it just right. I highly recommend placing the roofs first, THEN
figuring out where the cave/shelter will fit