I own this vaporizer: (product link) It has no electrical parts. To use it, you take off the cap at the left, put some "herbs" in it to smoke (vaporize), and put the cap back on. Then you heat the cap with a torch lighter until it says click. The click indicates that the cap (made of stainless steel) is at the right temperature. Then you can inhale from the right part and hot air with vaporized herbs will enter your body. It will click again when it has cooled down. (video)
How does this click work? Can I make this myself with a CNC machine?
The click system is at the end of the cap.