How to Draw Tubes in Illustrator

1. Select the rectangle tool and draw a horizontal rectangle.
2. Select the ellipse tool and draw an oval of the same height as the rectangle. Select the oval, copy it and paste it to obtain a second identical oval.
3. Place the oval shapes at the ends of the rectangle, overlapping the rectangle slightly, to form a basic cylinder.
4. Select the left oval and the rectangle simultaneously using the group selection tool. Open the Pathfinder palette and select Add to Shape Area from the Shape Modes section (first icon on the left). This will merge the left oval and the rectangle to form the outside of the tube. The tube should now appear open at the right end.
5. Open the Gradient panel. Select the new shape you just created (the left oval and rectangle) and fill it with a three-color gradient. Use a dark color shade for the gradient stops and a lighter shade for the midpoint. Set the gradient angle at 90 degrees and the location at 50 percent.
6. Select the right oval and fill it with the same gradient as the first shape, but set the location at 60 percent to offset the gradient slightly.
7. Adjust the gradient color, lightness and angle as needed.
8. Rotate the tube shape as desired.