Roy McNeill wrote in a message to Niels Petersen:

 RM> Here's a semi-related question - is there an economical way of
 RM> buying or making a 2 or 3 metre long straightedge?

Take a three meter length of straightish bar. Place it on a flat surface
and draw a line thus:


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Scribe a perpendicularish line to the two points corresponding to the ends,
then turn the bar over so it is the other side of the line [over the top].
Draw the line again. Where the lines do not correspond, you have some
filing to do.

Welcome to 20,000 BC.

Terry

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