A reaction plate (10) comprising a welded plastics planar laminate consisting of an aperture plate (12) and a film (22), the aperture plate (12) having at least one planar surface and a plurality of apertures (14) in the planar surface of the apertured plate (12) and the film (22) being attached to the planar surface of the apertured plate (12) around the or each aperture (14) by welding. A method of forming such reaction plates (10) using diode laser welding. An apparatus for handling such reaction plates (10) including performing polymerase chain reactions (PCRs) or primer extensions therewith. The welding is preferably laser or transmission welding.