The old boat builders used strings to scribe water lines on hulls.

Use two string lines. For ease of setup have the strings parallel and level
to where you want the line to go. Site through the strings onto the
hemisphere and make a pencil mark every 6 to 8 inches. (an extra person
helps) Get a flexible baton (thin, straight stick) and connect the marks.

Good luck.

Eide

"Catherine Jo Morgan" wrote in message
...
I think a small laser level would help me a lot, but I'm not sure. Let's
say
that I have a curved surface, a rough hemisphere for example. I'd like to
cut the hemisphere in half, or at least slice it so the cut edge is
straight
and can be fitted onto a flat surface. Could a laser level lay a straight
line onto the curved surface, so I could mark it for cutting?

Perhaps there's a better way to do such marking? I know a laser level will
give me a pretty broad line at close range. Is there a way to distinguish
among the different models to find the one that will have the thinnest
line
at close range? Are the lines or dots always smaller the closer you are?

Also - would it be kind to my eyes to wear shaded glasses when using a
laser
level? I do know not to point the laser AT my eyes (or at anyone else.)
But
the line itself is pretty bright, right? So maybe shade 3 if I can find
some
clip-ons? TIA
--
Catherine Jo Morgan
http://www.cjmorgan.com
online artist journal: http://radio.weblogs.com/0120691/