Help 1jz custom manifold design

[onlydrinkkoolaid 240Love]

Ok I just brought this Tig welder with the hopes of fabricating a custom 1jz manifold for cheaper then the labor inflated 1000+ manifolds no knock on them just cutting cost with the trade skills I have picked up along the way. I have all the desires to do a high horsepower design but have no idea on what size piping, flange thickness, and metal for best durability.....

Please any suggestions would help and maybe a quick measurement around the pipe on a top of the line design no knock on anyone who doesnt have one but your suggestions are welcomed too...