DIY Ultrasonic Mist Maker

[kalel]

Here's an interesting video from GreatScott



Those prebuilt modules can cost as low as $3-4 (maybe the eBay price in the video was with power adapter) and seem to work well.

How would you make one? Do you know of any cheap ways that would be effective? This is generally pretty advanced stuff for me, so I wouldn't be able to think of such a circuit.