In 2001 the artist created an installation at the C.A.C. of Bellinzona entitled “Oh le nuvole!” ("Oh the clouds!") in which, for the first time, clouds appeared as an element of the installation. Subsequently, Luisa delle Piane organized a collective on the theme of lightness, which inspired the cycle of Castelli in aria, based on an idea the artist had already worked on, using sand and glue in 1990. These are installations, sometimes even of several square meters, in which small clouds made with cotton balls hang from the ceiling on whose surface there are small houses and cardboard castles.