This is the rectangular home made version.
No plasma or laser cutter required.
Nothing you can not do with a modern saber saw, sawsall
or hole cutter. You will need some tig welding for the overall
p-port manifold and slide throttle.
I am sure Ed Klepeis can make the whole thing for you
if you ask.

The Teflon is 3/8" thick and front and rear plates
are 3/16" so the 2 inch runner tubes can be directly tig
welded to them. There will be more drawings and 3D's shortly