how to make a electric steam vapourizer at home
I built a very durable steam vapouriser using a standard electric kettle, and a way of supplying it with a reduced power. This has the advantage that the vapouriser is cheap, readily available, is run well below its normal power rating so should last forever, and can be plugged in directly at first to heat the water quickly, before going to reduced power for long term steam generation.

Being an engineer, I happened to have an auto-transformer to hand. However, it is easy enough to buy fairly cheaply fixed transformers, or variable power controllers for heaters like this. Don't use a conventional lighting controller triac dimmer, it won't have the current capacity, unless you use a very low power kettle like a tiny 'travel kettle'. Choosing the amount of reduced power going to the kettle gives you a choice of the rate of steam production.

If you are happy with wiring mains components yourself and doing it safely, then wiring a light bulb or a motor-run capacitor in series will reduce power to the kettle.