19. Select all objects.

20. Next click Modify > Combine > Punch. This will create a series of composite objects from the original shapes.

21. While the new composite objects are still selected, click Modify > Split. This will separate the composites into individual closed paths. We will need to open all the closed paths so put the drawing into Keyline mode to make it easier to work with them. Each of these shapes has three line segments. In each of these closed paths we need to delete two of the three segments leaving only one open path remaining. Note: Some of the closed paths have an additional segment due to the fact that each circle was comprised of four points. Since each circle was divided into five parts, this accounts for the extra points and line segments resulting from the combining of objects in a previous step.

22. Select one of the closed paths. It doesn't matter which one. Option+click (Macintosh®) / Alt+click (Windows®) one of the segments to delete. You can delete the segments one at a time or you can press Shift+Opt+click / Shift+Alt+click to select both segments at once. You can tell that a line segment is selected because the points will be hollow, not solid.

23. Press the Delete or Backspace key. What remains is an open path in the shape of an arc.

24. The previous steps need to be repeated for each of the remaining closed paths. Select another closed path in the section being worked on and select two of the segments similar to a previous step.

25. Once again, press the Delete or Backspace key leaving an open path in the shape of an arc.

26. Repeat the previous steps for the remaining closed paths in the section.

27. Continue to repeat the previous steps for each of the remaining closed paths. Open them one at a time so that only the arcs remain.

28. Switch back to Preview mode.

29. Select all of the arcs.

30. Once again, bring up the Stroke Inspector. Click the round "Cap" button (circled below).

31. This will give a rounded cap to each path.

32. Finally, while all the paths are still selected, click Modify > Alter Path > Expand Stroke.... Each path is 8 points wide, so just click "OK" to accept the defaults and close the dialog.

33. Each open path will convert to a closed path...

34. When you deselect everything, your workspace should look similar to the example below.