How to Draw Connecting Shapes with Multiple Strokes with Adobe Illustrator

© 2011 Ugur Akinci
Sometimes you will need to draw technical illustrations with shapes that not only connect but also have double or multiple strokes. Think of converging railroad tracks.
A shape like this:

Follow these steps:

(1) Draw your individual overlapping shapes by using any tool necessary (rectangle, ellipse, etc.).
(2) Press Ctrl + F10 to display the STROKE pallet. This is where you set the thickness of your strokes to anything you like.

(3) Press Shift + F6 to display the APPEARANCE pallet. Make sure your fill is ZERO (no fill).
(Click to enlarge the images)

(4) Add a SECOND STROKE layer in the APPEARANCE palet. Give it a different color and then reduce its stroke size in the STROKES palette:

TWO stroke layers of different color and width on top of each other will create the illusion of a multi-stroke object.
(5) While all the objects are selected, press Ctrl + 8 to create a COMPOUND PATH:

You’re done!
Play with different stroke sizes and colors for different effects: