Create a "Black Box" Pool

1. From the Elements Palette, click on Create Pool/Participant icon. 
2. Move your cursor onto the Canvas and click to position the new Pool on the Canvas.
3. Select the newly created Pool. 
4. From the Context Pad that appears above the new Pool, click on the Change Element icon (it looks like a rectangle on top of a circle).
5. From the list that appears, select Empty Pool/Participant.
6. Double-click on the "Black Box" Pool to add or edit its label.

An example of creating a "Black Box" Pool in Camunda Modeler.