I think a center line finder is for finding the center on the ends of round stock.

[Kenny_S]

I have one that was displayed on picturetrail and have to agree with ALA as the one I have was shown as a reference line marker. But like ALA, I have been wrong. Anyway, I use it to mark reference lines of equal lengths like a coat on a subject.

[Kenny_S]

I forgot to add and maybe I shouldn't but Danny Reb,Woodcarver from Sherman Tx is the one who made the one I have. Gots to figure out how the little bride uploads pictures. Funny thing about us, I worked 35 years in an Information Technology department for a majopr Oil company and she is the one showing me. Hehe, goes to show you what teachers do!

The center finder is a very simple tool to use to find the center of the wood (square or round). I use it also as a reference line guide to keep the carving even; hairline, eyes, ears, shoulders, elbows, and etc.. It is also very helpful to lay out your pattern on a block of wood or eggs.
Have a great day,
Tim