In 1975, Emilio Prini opened the exhibition Mostro – Una esposizione di oggetti non fatti non scelti non presentati da Emilio Prini at Galleria Toselli in Milan. The artist closed the entrance of the gallery for the entire duration of the exhibition and constructed a small window space, painted in yellow. Here, the artist displayed a red and white Knoll swivel chair with two sheets of paper placed on the seat, bearing the text: “Io Emilio Prini autentico da me non fatto non scelto non presentato questo oggetto (I, Emilio Prini, authenticated by me, not made, not chosen, not presented this object), dated 1974” and bearing the inscription “Mostro- una esposizione di oggetti non fatti non scelti non presentati da Emilio Prini © Toselli Milano (2nd proof)”. In the background, the phrase from the 1958 song Brivido Blu by Tony Dallara “…sei come un’atmosfera che dona un brivido blu…” (…you are like an atmosphere that gives a blue thrill…) appears. Later, Prini would make a life-size enlargement of a photograph of the entire shop window, taken during the exhibition, printed on paper and framed using the original gallery door frame, thus obtaining a cast of the exhibited object. During the same year, the artist would also conceive an evocation of the work, producing a second display case using the same image, but mounting it in a smaller frame and without a lock.