Very useful thread -- pictures of presses, and links to other pages w/pix, on thread's Page Two. Tips for shield making with them, too.
Like something I wish I'd thought of: double-length eight foot long (six- or seven-footer could get it done too) shield press that makes shields two at a time, after making one lengthwise halving cut down the 4x8 sheet of 1/4" ply, glue and press the entire sheet at once, making two blanks at any one time. All easy PC lemming squeezy.
Presses of this open ended description can press out ply blanks that lap out at each end if they must, perhaps with some use of clamps at the ends of the blanks to make sure of the glue bond out there. A press that pushes ribs into a quadrangular frame would require the ends of the frame to be built to give room to any over-length blanks -- not have those ends just straight across on the same plane as the sides. They need to be cut out into an arc, from bigger lumber, or otherwise displaced downward to give room. This doesn't become a problem for presses with nothing but arched former-ribs pressing into the negative cutouts that are the other halves of the planks these ribs were cut from. These presses' ends are just a couple more of these formers and cutouts and thus the overlength blank is free to stick out and still become formed.
