Step 1: Find a machinable material that is reasonably incompressible.
Step 2. Find a string material that is reasonably non-stretchy.
Step 3: Make a cylinder out of the machinable material (perhaps using a lathe).
Step 4: Make a fine groove in the cylinder, of even depth and non-wavering axial elevation. (The lathe can do this, too.)
Step 5: Wrap the string around the cylinder (in the groove).
Step 6: Cut off exactly one lap of the string.
Step 7: Measure off however many even increments you want along the string. (You can do this by making a set of evenly-spaced parallel lines, and placing the taut string between points on the far parallel lines. The number of parallel lines needs to be one more than the number of increments.
Step 8: Put the marked-off string back in the groove.
Step 9: Optionally, secure the string in place.

Note that steps 1-5 are equivalent to using a compass to draw a circle on a paper. Step 6 is a way to straighten out the circle back to a line segment. Steps 5 and 8 are a way to wrap a line segment into a circle.

Step 1: Find a machinable material that is reasonably incompressible.
Step 2. Find a string material that is reasonably non-stretchy.
Step 3: Make a cylinder out of the machinable material (perhaps using a lathe).
Step 4: Make a fine groove in the cylinder, of even depth and non-wavering axial elevation. (The lathe can do this, too.)
Step 5: Wrap the string around the cylinder (in the groove).
Step 6: Cut off exactly one lap of the string.
Step 7: Measure off however many even increments you want along the string. (You can do this by making a set of evenly-spaced parallel lines, and placing the taut string between points on the far parallel lines. The number of parallel lines needs to be one more than the number of increments.)
Step 8: Put the marked-off string back in the groove.
Step 9: Optionally, secure the string in place.

Note that steps 1-5 are equivalent to using a compass to draw a circle on a paper. Step 6 is a way to straighten out the circle back to a line segment. Steps 5 and 8 are a way to wrap a line segment into a circle.

Step 1: Find a machinable material that is reasonably incompressible.
Step 2. Find a string material that is reasonably non-stretchy.
Step 3: Make a cylinder out of the machinable material (perhaps using a lathe).
Step 4: Make a fine groove in the cylinder, of even depth and non-wavering axial elevation. (The lathe can do this, too.)
Step 5: Wrap the string around the cylinder (in the groove).
Step 6: Cut off exactly one lap of the string.
Step 7: Measure off however many even increments you want along the string. (You can do this by making a set of parallel lines, and placing the taut string between points on the far parallel lines. The number of parallel lines needs to be one more than the number of increments.
Step 8: Put the marked-off string back in the groove.

Note that steps 1-5 are equivalent to using a compass to draw a circle on a paper. Step 6 is a way to straighten out the circle back to a line segment. Steps 5 and 8 are a way to wrap a line segment into a circle.

Step 1: Find a machinable material that is reasonably incompressible.
Step 2. Find a string material that is reasonably non-stretchy.
Step 3: Make a cylinder out of the machinable material (perhaps using a lathe).
Step 4: Make a fine groove in the cylinder, of even depth and non-wavering axial elevation. (The lathe can do this, too.)
Step 5: Wrap the string around the cylinder (in the groove).
Step 6: Cut off exactly one lap of the string.
Step 7: Measure off however many even increments you want along the string. (You can do this by making a set of evenly-spaced parallel lines, and placing the taut string between points on the far parallel lines. The number of parallel lines needs to be one more than the number of increments.
Step 8: Put the marked-off string back in the groove.
Step 9: Optionally, secure the string in place.

Note that steps 1-5 are equivalent to using a compass to draw a circle on a paper. Step 6 is a way to straighten out the circle back to a line segment. Steps 5 and 8 are a way to wrap a line segment into a circle.