"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.

My usual solution to this problem is a lot less technical.

First, stand your object on a flat table, preferably clamping it so it
can't move, with your intended cut plane horizontal.

Then, hold a pencil horizontally on the top of a block of wood, with
the point sticking out over the edge a bit. Pick the height of the
block so the pencil point is at the cut height.

Now you can slide the block around on the tabletop all you like, and
the pencil tip is always at the same height. Just slide the block
round the object, drawing your cut line as you go.

It's not a super-accurate solution unless your table is very flat, but
it's probably better than marking from the laser line.