Click Curve\Cylinder - the brush becomes a patch.  Get a side view and stretch the cylinder upwards to make it into some sort of chimney-type pipe.

Click on the metal_c07a texture to texture the cylinder.  The texture will probably look all stretched and horrid.  Press shift+S and click natural and done.

Note that only the outer surface of the cylinder is textured, the inner is effectively nodraw.

Let's warp the pipe.  Press V and get a side 2D view.  Filter the models (shift+M) to make the view clearer.  Zoom in.  Note that the middle height points may not fall on a grid intersection.  If not, drop down the grid scale until they do.

In my example, grid 3 will do.  Warp the tube in interesting ways by grabbing the illuminated vertices and dragging them, one at a time.  The cylinder will warp as you drag the vertex point.  In my example, I've dragged the top vertices to the left somewhat, and I've dragged the middle ones up, and outward to give a leaning, bulging cylinder.

Experiment, using different 2D views, to see what sort of weird shapes it is possible to create.  You can also drag edges in 3D view, but this is trickier.  Press V or ESC to cancel vertex mode when you've experimented enough, but leave the brush selected.

If you want to cap the open ends, and create a solid-looking cylinder, click Curve\cap selection.  The top and bottom are neatly capped, and the three brushes are grouped for you automatically.  We don't really want the bottom cap, so a quick way of getting rid of it is to change to grid scale 9, lift the group one notch so you can see under it in 3D, deselect the group and then select the bottom brush alone and delete (Backspace) it.

Then select the group (now only 2 brushes) with shift+alt+click and put it back down one notch.

If you want to see how your weird cylinder came out, save compile and test.

You can of course rotate these patches just like any other brush.  But if you scale them, watch out!  Scaling downward may result in some of the critical control vertices not aligning to exact grid co-ordinates, eg instead of a co-ord being (24, 56, 44) you might get (24.043, 56.324, 44.985), which tends to make things crash.  :(

So if you have to scale a cylinder (as I did when I wanted to make my V-1 creation of multiple cylinders about 75% of its created size), you will need to examine all the component vertices in close up, with a grid scale of probably 1, and drag to intersections any vertices that fall in the gaps between them.

Click Curve\cone.  The brush becomes a conical patch.

Move it up onto the roof.

My example looks like the nose of a V-2 rocket.  But you can change the shape of a cone by using the Vertex tool, just like with a cylinder.  Try dragging the vertices around to create a rounder or a fatter cylinder, whatever you need.  If you need finer control of the shape, you can add more vertex points: click Curve\Insert\Add 2 rows.

You can get some really weird shapes by dragging these vertices about.  You can make some very intereting sculptures...

Out in the new space we will create a curving path.  Hide the ceiling so it doesn't get in the way.  Select grid scale 5 and zoom in a bit.  Then create a brush as shown.  You can show models again now if you like (shift+M).

Move the brush down until it sits on the ground.

Make sure you have the overhead 2D view.  Then click Curve\Simple Patch Mesh and click OK.  This turns the brush into a patch of the same area as the brush, but with no depth.

Make the road curve by pressing V and dragging the vertices as wanted.  I've made a gentle curve of uniform width for its length, by dragging all the vertices in the same row by the same amount, whether to the left or the right.

Press V to turn off the Vertex tool.  Next we'll give the curve some depth.

Click Curve\Thicken... then as we want the curve to be 16 units deep (just so it touches the ground in this example), enter 16 and click OK.  You get a chunky curve like a piece of scalextric track, defined as a group.  We can delete the bottom face like we deleted the bottom cap of the cylinder, by lifting the group, deselecting it, selecting and deleting the bottom face, selecting the group again and putting it back in place.

You can create upward/downward slants in the curved path by lifting its vertices up/down before applying the Thicken.

You don't have to worry about Detail brushes for patches, ET treats them all as detail anyway.

Save, compile and check out your creations.