This was a fun day. Finally got my shipment of aluminum angles for longerons and firewall stiffeners, so I am off to the races. Got the firewall finished up and clamped into place. Then cut and formed the lower longerons. I clamped the upper longerons into place just so I could get image #3 below, but they still need some cutting and forming before they are really ready. But it is now actually starting to look like a plane skeleton.
The angles rivetted to the aft surface of the firewall
Left lower longeron in place between center section and firewall.