There are a bunch of KFL and R91 threads that you can search for. For a cool vape, perhaps something around 2ohms? 28awg Kanthal should work fine. I use Ekowool, although silica and cotton would work too. I like to vape 1.3ohms to 1.5ohms on a mechanical (4.2v to 3.7v), but I like "low resistance" and a warm vape.