For more details EventStorming workshops, you would need more or less the same things as for the Big Picture workshop:

• Paper roll or any other type of unlimited modeling space
• Sticky notes of different colors, we get to the notation later on
• Enough permanent markers

Of course, the essential ingredient is to have the right people. But now we get deeper into the details so it is essential to choose one area that we shall explore and finding such space is often a non-trivial task, which we will discuss later in this chapter. So, the right people would be those who will be busy writing the code, someone who is responsible for that part of the system as a product owner, and domain experts in the chosen area. As you can see, we can limit our group too much fewer people compared with what we dealt with during the Big Picture session. 

Both options: limiting the scope and limiting the number of people, allow us to discuss the design in the much higher level of details, have one single discussion thread and have everyone to express their thoughts and ask questions.