I`ve present my mods along a many forum, so if I arrived here why not:
Tubes are made from dural (aluminium alloy), have booster inside at 4.2V fixed, or other desire value, 5 click on/off, sensor for vape. Have Revers polarity protection and short circuit protection.Some random pictures:
Thanks . Yep I`ve been asked to make with blue led and this is.
Anyway In background are many hours spending on building and testing electronics for a good vape.