Just caught wind of this thread. Super interesting.
You're right about the tech advancements paving the way for cloners, so keeping this sort of thing open source is a good idea. I could see the dry herb 510 friendly world becoming popular in the upcoming years. The idea of being able to customize your setup in a modular sort of way is so appealing for some reason..
Cannabis and creativity go hand in hand I think.
Also, you can order mica tubes in pretty much any size. I would look into it for the ID of the coil chamber, could be a cheap way to insulate a steel tube and keep it from robbing the heat.
For the heater wire, there is a ton of open dead space where most of the air is passing by unheated (at least that's my opinion). Instead of focusing on a way of creating turbulence before or after the coil, why not create the turbulence inside the coil with a matrix more like a mesh or honeycomb. Hairdryers, for instance, have been doing this sort of thing for years.
Heating air is different that heating liquid in contact with a coil. So there needs to be a departure from e-cig tech here, I think.
But don't get me wrong, this whole thread, and the bulli thread, is massively inspiring.. and it seems like you guys are achieving great results anyhow.
I'm not too well versed in coil building also, and I'm sure there is something I am missing, such as the electron flow through a foam medium (if using a SS metal foam element, for example)..
What about twisted or wrapped coils?
Also, take a look at this In-line cartridge heater with a long coil mounted in a ceramic housing.
What are the disadvantages of using a longer coil like in this cartridge design to get more efficient heat transfer to the incoming air? You could probably use a lower coil temp.
Another idea would be to make a coil out of flat wire, and coil it tightly into a spiral like a car cigarette lighter, with overall diameter of the coil equal to the inside diameter of your insulated chamber, so the air is forced through this tight spiral...
Really, there are lots of ways this could go.. I'm excited to see what people experiment with!