@sony1492 Yup, round tube everywhere except the floor, firewall, and some other "internal" pieces.
The firewall in my build is split into two pieces, one for the engine side and one for the passenger side. That left a pretty large hollow spot at the floor behind the seats, which is covered by a removable section of the firewall.
The fuel is pretty close to the people, but if my gas tank gets crushed, leaking fuel will be the least of my worries.
e1d8f986-4ec6-4f59-ac8e-973e11386f85-image.png
(Best pic I have right now. I need to do some cleanup in the garage to get some newer pics.)