Trainspotter is a small building near the railway, at the edge of a residential neighbourhood. The edifice, elongated and with a single pitch roof, is unused and doesn’t contain any comfort nor toilet facilities. The landlord invests a limited sum of money following the proposal of a future tenant, in order to transform it into a one person dwelling. Self-construction principles make this project possible: it consists of simple operations, dry-construction techniques and common materials. The first step is clear the interior volume of the partition and ceiling, for taking advantage of the full height measuring five metres. One tall volume takes shape, and at one end of it stands a three metres tall timber volume. This is a device that reconfigures the space by hosting the kitchen equipment and a ladder on its front, a bed and wardrobe on top, the toilet and the boiler inside. The surfaces are coarse, the furniture is essential. The pig iron wood-burning stove completes or substitutes the radiators’ heating system. The screed hosts the installations and serves as flooring: its refined and polished surface reveals the aggregates. Trainspotter is a way to design and a way to live. In 2018 it is dismantled and transformed according to new necessities.