I think kipkay did a video on that... http://kipkay.com/section/videos/lasers/He's done a bunch of videos on how to make burning lasers! I think you can use a blue laser from a DVD writer or Blueray reader as your diode... Be careful if you try this; you might blind/burn yourself!
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https://www.instructables.com/member/icinnamon/Go then click on the laser pointer instructable.
A laser pointer is a 5mW (milliWatt) laser diode/laser LED connected to about 5 volts/3 button cells. You need over 100mW to get hot, and that's just barely enough to pop a balloon.