Abstract: A process for placing at least one fiber element on a surface is disclosed so as to provide a deposited fiber element having a width that varies longitudinally. The process may provide a step in which the width of the fiber element is modified upstream of the deposition step using a width control device. A device for performing the process is also disclosed. Further, fibrous sheets containing one or more deposited fiber element having a width that varies longitudinally are also disclosed. Preforms formed from one or more of the fibrous sheets are also disclosed.