I especially like plumb bobs.
Plumb bobs are what carpenters and masons use to find straight vertial lines.
They come to a point at one end and have a way to attach a string, usually a screw-on top. Now the carpenters use lasers which probably work better but aren't nearly as pretty. Old plumb bobs are usually made of brass, in curved or angled shapes that come to a point. There's something very appealing and graceful about them. Some day you'll be able to click here for a picture of my collection.