Re: Convert Fill Line to Stroke in Illustrator CS3
If each line segment is a rectangle, and you need to replace them with stroked lines in the center of the rectangles, try the following:
Select all horizontal rectangles, then Object > Path > Average..., then "Horizontal" in the dialog window. Repeat for vertical rectangles, choosing "Vertical." Then remove the fills and apply strokes to the paths. Each path will actually be a rectangle with zero height or width, so you should use the "delete anchor point" tool to delete one of the redundant points on each end, thereby making a line with two points, otherwise the die maker may have trouble with it. You might want to join all of the corners together afterwards (this is how I make dies, but I don't honestly know if that is how the die makers prefer it). If you have rectangles that are not strictly vertical or horizontal, you might try rotating the entire die by the appropriate angle, converting the rectangles, then rotating back.
The above will only work if each segment is a rectangle. If you have, for example, a rectangular die, and the artwork is a filled compound path of a small rectangle inside a larger rectangle (instead of a single rectangle with a stroke), you could remove the outer rectangle, and offset the inner rectangle using Object > Path > Offset Path... by the appropriate distance to get the path properly centered within the original line.