Abstract: A lightweight, substantially hollow filter plate constructed of foam molded thermoplastic material is formed by two separate identical plate sections each having a forward and rearward face. In a recessed type plate, the peripheral area of the rearward face of each section includes a plurality of support ribs arranged in lattice type configuration. In one embodiment the plate sections are integrally joined together with their rearward faces opposing each other and with the support ribs of one section butting against the opposing support ribs of the other section to produce a cellular construction light in weight but yet sufficiently strong to withstand the operating pressures normally associated with standard filter press machines.