The invention provides a method and apparatus for depositing soluble materials on flexible substrates. The apparatus comprises a drum, which is rotatable about its longitudinal axis, and an inkjet print head disposed over the drum and adapted to be moved relative to the drum in a direction substantially parallel to longitudinal axis of the drum. A substrate is mounted on the drum by vacuum means and a line of droplets of a solution of the selected material is deposited by the print head, which remains stationary as the drum is rotated. The print head is then moved relative to the drum, in the direction substantially parallel to longitudinal axis of the drum, prior to deposition of subsequent lines. In this way, electrical devices can be built up on the substrate and a large scale flexible display device can be fabricated.