The man I could recommend was making a one off fuel tank today, he would no doubt fold the metal on his 8 foot folder so you get nice neat edges etc, but there's a lot of satisfaction diy, maybe spray afterwards, but I understand if you want a pro looking one.
There's seriously nothing technical about the design a box pipe and ideally media inside, which bailey don't have, would make a much more effective breather, the important pipe is the breather itself, and the media that stops the oil laden fumes escaping, scrub buds are good for this.
tabetha