Fuel Cell......like round, or cubular??? /forums/images/graemlins/tongue.gif
If it were me and it were cubular-shaped, I'd build the whole thing except for the top. Start by welding up all the interior joints, then weld all those same joints from the outside too......that should pretty much guarantee no leaks.
Think about baffles and stuff too, though....and vent lines, feed lines, and a hole for the fuel sender, maybe a bung at the bottom to drain the gas if you ever needed to.
If you're going to build your own, you should really do some good baffling (though it might....uh, baffle you) Figure out what it would take to keep fuel in the pickup tube area NO MATTER WHAT angle the tank is on. I don't know how to do that....but I will figure it out before I weld the top panel onto my tank/cell.
/forums/images/graemlins/thumb.gif