The project arises from the decision to locate the ARRUGA film studios in an industrial estate on the outskirts of Barcelona considering the production of films and commercials as an industrial activity. Thus, a building destined to house a creative activity was confined to coexist in a grey world, without language, like factories and warehouses with the typical hourly activities of industrial estates. Faced with the impossibility of generating a language with its "neighbours", the building becomes an image and reflection of its own essence, showing itself in the only possible way: a building for making films. When it gets dark, the main façade becomes a piece of celluloid, becoming the very activity of the building such as production, post-production, realisation, etc. The rest of the programme is hidden behind the blind box; casting, costumes, props, assembly warehouses, workshops, dressing rooms and services. Finally, the large space intended for the cinematographic set is presented to us in its most neutral form. The construction (materials, structure and installations) of this space is put at the service of the main activity, reinforcing the neutrality of the project. The building is constructed with the technique and prices of an industrial building; an exposed steel structure with fire protection, forged ribbed iron decks, concrete block walls, polished concrete floors, exposed installations and a façade of cement-wood counters. The project incorporates as an external element a linear plantation of Populus tremula a short distance from the main façade. This plant formation reveals to us a new negative interstitial space of the interior. This space relates the internal activity to the external space at the same time as it uses their changing condition. In the summer, a thick green mattress will protect it from the sun, in the autumn it changes colour and clears the leaves, in the winter it becomes a reflection on the large, glazed window, and in the spring it will show the different shades of green. Between this screen of trees and the street of the polygon, an open space is designed for the arrival and circulation of vehicles. Finally, in an industrial estate, a grey box raises a question of architecture; the tension between the envelope and the internal space articulated by the light.