Okay I'm curious if this idea is even possible. 22mm atty with top air intake but routing the air to the bottom under the coils.
My idea was maybe a smaller internal chamber say 18mm and letting the top airflow feed via the space between the 2 chambers to create the under coil air flow. Advantages are bottom air for flavor production, virtually leakproof via use of top air intake and of course a conical top for the inner chamber to enhance flavor.
see.. Manta2