Abstract: A device for installation for forming fiber mats, the fibers being formed from a material that can be drawn by internal centrifuging and by drawing by a gas current. The device includes a guide duct into which the fibers are designed to be channelled, with a longitudinal axis including a first portion configured to form the entrance of the duct at which the fibers are designed to be inserted into the duct, a second portion or central portion, and a third portion configured to form an exit of the duct, and an articulation mechanism to act mechanically on the third portion of the duct to cause its dimension and/or the position of at least one of its portions to vary relative to the longitudinal axis.