He might try glass fibers. That was one of the original uses for
glass filaments discovered by accident when a researcher at Owens
Corning blew compressed air at a mass of molten silica in an attempt
to cool it. Some of the first fibers were used to create the cross
hairs for the top secret Norden Bombsight installed in US bombers.
The story goes that the guy that developed it made a ton of strands,
and after selling the US military all they needed for gun sights,
was left with something like 99% of the fibers he made. He and his
fellow researchers who were messing around with different plastic
resins mixed up some experimental epoxy resin and used it to patch up
a broken wicker chair. So, like so many other ingenious inventions,
what they created accidentally would come to be a very important,
life-as-we-know-it changing new material, known to the world as
This story was told to me by the son of one of the researchers at a
seminar on creating molds for making fiberglass aircraft parts, so I
can’t really stand behind it if someone wants to pick at some nits.
But glass fibers would most definitely work as cross hairs in
optical equipment and are available in sizes that would be pretty
hard to find in metal. Cheap too.
A buck and a half would probably buy enough to make a thousand cross
hairs. Wrapping it and putting it under tension might be problematic,
but doing the same with 0.0005 steel wire is going to be a bit of a
challenge too, I would guess.