Now that you've got everything patterned out it's time to cut it all out. Start out by tracing it all out onto your steel, make sure to place your pieces to minimize the amount of waste. This was especially important for me since I had just BARELY enough steel to finish this helmet.
Once your happy with the layout fire up your jigsaw and start cutting out the brow band, bands and top. Do not cut out the cheek plates, nasal or slats until you have the dome of the helmet assembled.
Once you have all your top plates cut out clean up the edges and put a nice bevel on them. You don't want to have any burrs or sharp bits anywhere on them. Any point that may come in contact with you should be rounded out.