Method for manufacturing a recess plate to be used in a filter device for filtering a suspension, the filter device having a stationary head piece and a movable end piece, and a pack including copies of the recess plate, having a filter chamber inside the pack, adjoining the recess plate, having a first pipe for filling the suspension into the filter chamber, having a filter cloth for collecting a solid content out of the suspension, and having a second pipe for discharging a liquid fraction of the suspension out of the filter chamber as a filtrate, wherein the filter device may be closed before filtering by forcing the end piece in direction of the head piece, and opened after filtering by releasing the end piece, and moving the end piece away from the head piece for removing the filter cake from the filter cloth, wherein a. a first sheet is formed to provide a first surface of the recess plate at the filter chamber, and a second sheet is formed to provide a second surface of the recess plate vis-à-vis the first surface, b. by forming the first sheet to provide a first surface of the recess plate at the filter chamber and the second sheet to provide a second surface of the recess plate vis-à-vis the first surface includes inserting a stack of the first sheet from fabric, soaked with hardening resin and of the second sheet from fabric, soaked with hardening resin, each of the first sheet and the second sheet is lined by two protective sheets (4, 5), between two female solid molds, c. pressing and claiming the two female solid molds together to seal recesses inside the female solid molds, d. feeding fluid between the first sheet and the second sheet for pressing the first sheet and the second sheet into the recesses, e. discharging the fluid and opening the two female solid molds, f. removing the protective sheets from flip sides of the first sheet and the second sheet, g. reversing the first sheet and the second sheet to have the flip sheets of first sheet and the second sheet to face each other and mounting the first sheet and the second sheet to a frame containing all the drills and bores required for filtrate, wash water, and air, and h. filling a spacing between the first sheet and the second sheet by a rigid body, wherein a foam is injected between the first sheet and the second sheet, that after hardening forms the rigid body. a. a first sheet is formed to provide a first surface of the recess plate at the filter chamber, and a second sheet is formed to provide a second surface of the recess plate vis-à-vis the first surface, b. by forming the first sheet to provide a first surface of the recess plate at the filter chamber and the second sheet to provide a second surface of the recess plate vis-à-vis the first surface includes inserting a stack of the first sheet from fabric, soaked with hardening resin and of the second sheet from fabric, soaked with hardening resin, each of the first sheet and the second sheet is lined by two protective sheets (4, 5), between two female solid molds, c. pressing and claiming the two female solid molds together to seal recesses inside the female solid molds, d. feeding fluid between the first sheet and the second sheet for pressing the first sheet and the second sheet into the recesses, e. discharging the fluid and opening the two female solid molds, f. removing the protective sheets from flip sides of the first sheet and the second sheet, g. reversing the first sheet and the second sheet to have the flip sheets of first sheet and the second sheet to face each other and mounting the first sheet and the second sheet to a frame containing all the drills and bores required for filtrate, wash water, and air, and h. filling a spacing between the first sheet and the second sheet by a rigid body, wherein a foam is injected between the first sheet and the second sheet, that after hardening forms the rigid body.