These drawings by Maurice show the designs for the top and bottom platens.  We decided on a press bed (printing area) of 350mm x 350mm.  This enables the press to fit through a standard door width, which is useful if I am to be transporting it around.  We were also concerned that any larger and the pressure may not be high enough.  This is the first press we have built and it may not be the last, so we would very much like this one to work so that if we build a larger one, we can learn from the successes of this one.