How to draw a continuous overlapping line ?

[caitlinl3383977]

I’m trying to work out how I can draw lines with shadows, and which overlapping over each other that you can see clearly. Similar to the image I have attached. Thank you 

[Dave Creamer of IDEAS · Accepted solution]

Check out:

https://graphicdesign.stackexchange.com/questions/82409/adobe-illustrator-creating-a-plastic-three-d...