Comment by grues-dinner

The micro in this thing is a WQFN-16 (W = very very thin, thinner than V for very) with 3x3x0.75mm body. That's around a fiftieth of a gram of plastic.

I think the bigger SOIC chip is probably the battery charge IC. And then maybe a gram or two of PCB epoxy. And the plastic in the battery pouch and membranes which you need anyway.

In terms of plastics waste volume, the casing and tank is probably nearly all of the content. So the problem is a disposable vape bring a thing at all, not really the microcontroller in there.

It feels mad and somehow wasteful that you can get a CPU at that price point, but the die itself is a tiny sliver of silicon. You can even embed an (even tinier) and weedier application-specific) IC in a paper metro ticket. Compute is just so ridiculously cheap that you can have a hundred of functional ICs for the cost of a single largish cup of hot bean water.