I drew this while waiting for a friend last week. I was intrigued by the complex repetition of the metal trellis supporting a roof covering part of the plaza I was sitting in (and yes there was a cafe umbrella involved).

Metal roof support (and a cafe umbrella), 14 February 2014.

But the more I looked the more confused I became. From the angle I was sitting at the geometry was proving difficult to understand. So I ended up drawing one of the connection joints.

Joint for metal roof support, 14 February 2014.