My project proposes an adaptive framework for mass-customization of design for residential infill solutions. The proposed method focuses on a tough challenge of delivering minimal compact infill configurations for the urban context, where the square meters are expensive, and where the height is cheap. Industrialization of housing on the one hand and participation in design on the other hand are the key focus points of this thesis. The ‘open building’ approach is chosen to separate the building into two parts: the support and the infill parts. The support is considered as a collective flexible part of the 3D infrastructure of a city and the infill is considered to be a individual customizable residential unit of a building. The main question is focused on designing a computational method for ensuring mass-customization of housing infills with participatory mechanisms.