Ella, our Summer Breeze sailboat, needed a wind vane.
Ella has a "lug rig" sail, which is a setup that allows sailing fairly close to the wind, requires very little hardware, no complicated boom hinges, a lot of sail area for a fairly short unstayed mast. The problem is that there's no good place to put a wind vane: Normally you'd either put telltales on the shrouds (the cables that hold up the mast) or a vane on the top of the mast, but the highest spar here is at an angle, held in place by the luff of the sail.
So I went into the shop to see what I could do. The brass was all assembled from K&S structural shapes, the only extra cool bit is that the top of the tube which forms the vane bearing has a plug with a brass wire sticking down to form a needle bearing. The gimbal assembly is cut out of purpleheart, I cut the ring with a hole saw and the center of the ring with a Forstner bit, in the drill press. The weight is a hunk of, I think Ipe, because damn it was heavy and seemed perfect to hold the whole thing in place.
In that second picture you can see the range of motion this thing gets.
And in the last picture you can see it up on the spar. This was in my back yard, we're going over to camp at Lake Berryessa next weekend, hope to spend most of the weekend sailing in that northwestern arm, we'll see how well it does.