2a - How to Converting Strokes to Fills in Adobe Illustrator?
This instructional example is meant to generally demonstrate how to expand strokes and convert them fills so all like colors can be selected and changed at one time. There are many selection techniques which may work better for your unique art file. For instance instead of (select / all) you can try (select / same / stroke color) or (select / same / stroke weight). Experiment to see what best works for your art file.
Step 1: Open the art file.
Step 2: Select all strokes.
Please note: This can adversely affect appearances and gradients so it recommended to select only the strokes you want to convert to fills.
Step 3: Select EXPAND from the OBJECT drop down menu and click OK on the dialog box.
Step 4: Art should appear similar to the image below.