A chameleonic stage design for a night and day underground techno music festival at the old Monumental bull ring in Barcelona. This design-built proposal generates a floating roof that flies over part of the audience and casts a shadow over the stage. The roof, the background and the sides, made of micro-perforated white canvas, act as a shading element by day and as a light and video projection screen at night. This solution makes it possible to customize the stage in each edition of the festival through lighting and visual design.