This can be a piece of fabric like muslin, it can be white showcard, brown butcher paper to match warm tungsten lights. Most bounces are either fomecore, bead board, showcard or muslin. You can learn all about bounces, quality and quantity: https://www.filmmakersacademy.com/courses/how-to-use-bounce-light/
Budget-minded filmmaking forces you to solve your problems within limitations. However, given the importance of the visuals to engage the audience in the story, we needed creative control over every aspect of the film’s aesthetic.
