A curved tunnel using 3 pieces. As asked about in the forums.
Using a combination of VM and pyramids, the technique can be used to add more pieces. Because it is only three pieces, it is still slightly sqished in the middle, but it's hardly noticable.
edit: checked out the .map it looks pretty good! I wish there was a torus tool for hammer, but i guess it's fun trying to build these...
= )