I helped organizing it, my part was mostly organizing the workshops.
There were three: Christiaan Afman Veenema did "blind drawing and continuous lines", Julia Henze did Lettering of Urban Sketchers", and I did "Negative space".
The workshops were a huge success, not in the least because of the dedication of the participants. In my workshop they worked hard and concentrated, I did not make it easy.
Unfortunately I did not make pictures during the workshop, have to think about that the next time.
As teacher you don't have a lot of time left to draw, I only made 2 drawings. Will post them later.