I see this thread has gone on for a while but I found it interesting and wondered whether any of the original "experimenters" (
@bluewhistled,
@skwag,
@aturtles) - now that more time has elapsed, are still vaping B12.
Either way, as technology is still moving on, I wanted to suggest 2 additional options that might help partially or perhaps totally get around the primary concerns, particularly a) inhaling additional compounds that were not necessary or desirable, and b) the possibility of damaging the B12 at conventional vaping temperatures.
The first is of course temperature-control, which is fairly commonplace now. It's still maturing, but after a bit of a learning curve you can essentially limit the upper temperature of the coil - and hence the vapourized B12 - to anywhere from say 100C to 250C. Actual ranges are probably larger but I'm guessing where B12 is concerned anything outside those ranges is meaningless. Now... vaping at only 100C is not particularly satisfying, but heading towards 150C starts to work. Someone who knows more about the temperature at which B12 begins to meaningfully degrade (in only a few seconds) could suggest a useable maximum?
The second is the style of vaporiser that has become popular for "herbs", and by herbs I of course mean cannabis. This is essentially a very small oven, so the contents are vapourized without the need for mixing them with a liquid such as PG or VG. Temperature can again be set fairly accurately over a wide range, so if anyone knows the temperature at which B12 crystals vaporise, you could set the temperature just above that and get B12-only vapour. There is the volcano-style desktop thing, but handheld portable ones are now commonplace too.