The back of the chair can be flat, but bent much easier. How to do this? This does not require special equipment and technology is simple. Enough to have a furniture clamp and several supporting wooden beams. The middle of the plywood workpiece backless steamed over the spout of a boiling kettle. Placed it on two pieces of wood, steamed place of the preload clamp and leave for a day or two in this position the deflection will continue after the workpiece is removed load.