In Flatland light, panes of colour-effect-filter glass form a large, luminous quasi brick. The quasi brick is a three-dimensional space-filling form developed by Eliasson together with one of his long-time collaborators, Icelandic mathematician Einar Thorsteinn. The quasi brick’s form was inspired by Thorsteinn’s research into naturally occurring quasicrystals, which exhibit both four- and fivefold symmetry. The shape is a space-filling polyhedron – identical copies can be arranged together to ‘pack’ space, leaving no space between the individual members. The quasi brick’s combination of regular and irregular faces suggests an organic growth, but its geometric dimensions have been precisely tuned to achieve its unique properties.