To create a new path directly through the middle of an "S" shape, the exact technique depends on whether your "S" is an open vector stroke or a closed, filled shape (expanded text or outlined paths).
Here are the two easiest ways to achieve this in Adobe Illustrator:
## Method 1: For a Closed Shape (Outlined/Filled "S")
If your "S" is a solid, filled shape and you want to draw a perfect centerline (spine) through its middle, use the Blend Tool.
1. Cut the ends: Use the Scissors Tool (C) to click and cut the flat top and bottom end caps of your "S". Delete those two end lines so you are left with just the inner and outer boundary lines of the letter.
2. Open the Blend Options: Double-click the Blend Tool (W) in your toolbar. Change the Spacing dropdown to Specified Steps and type 1. Click OK. [1, 2]
3. Generate the middle path: Click once on an anchor point at the start of the inner line, then click once on the corresponding anchor point of the outer line. Illustrator will instantly draw a new path perfectly down the middle.
4. Expand the path: To make this new path fully independent, select the object and go to Object > Blend > Expand. Then, Right-click > Ungroup and delete the outer boundary lines if you no longer need them. [3]
## Method 2: For an Open Stroke (Single Line "S")
If your "S" is a single vector line with a stroke thickness applied, and you want to slice it or add a branch right from its middle section:
1. Add a point: Select the Pen Tool (P) or the Add Anchor Point Tool (+) and click exactly where you want the new branch to start along the middle curve of the "S". [4]
2. Draw the new path: With the Pen Tool (P), click directly on that newly created anchor point and drag outward to draw your new middle path. [5, 6]
## Method 3: Averaging Two Distinct Paths
If your "S" is made of two separate lines and you want to generate a third line directly between them:
1. Select the lines: Use the Selection Tool (V) to highlight both paths.
2. Use the Blend Tool: Click the Blend Tool (W), click the first path, and then click the second path.
3. Ensure your Blend Options (Double-click the tool icon) are set to Specified Steps: 1 to get a single, perfect middle path. [7, 8, 9, 10, 11]