Here is the 1st Extended Box in the key of C, a very useful pattern built around the 1st Box of the Blues Scale, great for diagonal phrasing.
Follow these steps:
1. Find the ROOT on the 6th (low E) string.
2. The 1st Extended Box starts from the ROOT. Ascending and descending fingerings are a bit different.
3. I use these patterns to play vertically and horizontally at the same time.
Check out the Blues Guitar Trick 3 already posted for another example in the key of A.
