I have always wondered whether I could partner with the inventors/engineers out there to produce a product that could bypass the lavatory smoke detectors.

Perhaps some sort of a contraption with a tube, a filter (acting like a sponge to sop up the smoke), a fan, and a cover for the smoke detector? Maybe some sort of variation of the desk-top smoke-sucker that I have seen in people's offices back when smoking was allowed in such places. I am not very good with mechanical things, so I have no idea if this is possible. I am sure that it is possible -- I guess the question is whether it would be practical to carry-on and how cheaply we could produce it? Judging from the responses here, perhaps there wouldn't be enough smokers desperate enough to shell out, say, $299.95 for such a device. . .

(Yes, I know, this would still be violating the laws and, taken to the extreme, perhaps present a danger for fellow passengers, but let's put those concerns aside arguendo.)