Show the list of your participants, run the draw in front of your audience and let chance pick the winners: everyone sees who is in the running before the name lands.
Two scenes in a row: the list of registered participants, then a random draw picking several winners among them.
Three scenes in a row: the participants on display, the prize draw, then the winners recap, fed automatically by the draw.
The introduction of the participants, a draw with the scene of your choice, its winners, then two more rounds open only to those who have not won yet.
Three draws of twenty-five winners running one after the other on their own, each round keeping only the participants who have not won yet.