A method of producing a device includes providing a substrate which has a recess. A multitude of loose particles is introduced into the recess. A first portion of the particles is coated by using a coating process having a depth of penetration which extends from an opening of the recess, along a direction of depth, and into the recess, so that the first portion is connected to form a solidified porous structure. The depth of penetration of the coating process which extends into the recess is set such that a second portion of the particles is not connected by means of the coating, and such that the solidified first portion of the particles is arranged between the second portion of the particles and surroundings of the recess. According to the invention, the second portion of the particles is at least partly removed from the recess.