For example, you are working on a mass celebration and you do not do the bubble show, but only take photos inside the bubble. In this case, it is better to have a separate tray without wheels. In usual practice, at weddings, anniversaries, use one tray with wheels both for performances and for a photoshoot. At events, pay more attention to your viewers who step out of the tray. Talk more, make you be heard, ask them to step out carefully and lift their feet higher.