This device, made by Francisco Sobrino, explores two essential qualities of the painting process: the act of mixing colour and the pursuit of representing shape. Combining a white background layer with two translucent, coloured layers – including a circular, moveable inner layer – these plastic sheets can be reconfigured to change the colour, angles and dimensions of the inner forms. Sobrino was one of the founding members of GRAV (Groupe de Recherche d’Art Visuel), a group of artists based in Paris in the 1960s who made artworks that invited an activation of their work. Untitled can be viewed as a fixed, completed arrangement crafted by the artist’s hand or a proposal for various arrangements of the moveable element of the work, which gives rise to a myriad of potential compositions.