Halloween falls on a Monday this year, giving you an excuse to celebrate it in the office—with a mini fog machine that fits in a coffee mug. This project, inspired by a water-only fogger from product safety engineer and DIYer Brian Clarke, employs sound waves to turn distilled water into a spooky haze. The tiny cauldron gives you all the boil and bubble of a witch’s brew for a lot less toil and trouble.


  • Time: 15 mins
  • Cost: $30
  • Difficulty: Easy to medium

Tools & Materials:


  1. Strip the ends of the battery box wires. Solder the negative wire from one box to the positive wire of the other. Solder the free wires of the battery boxes to the power plug. Then insert the batteries.
  2. Cut off and discard the top of the water bottle, leaving a bottom half that is about four inches tall. Place the fogger inside the bottom half with the power cable folded over the rim. Secure and waterproof it with duct tape.
  3. Plug in the fogger, place the batteries in the bottom of the mug, and set the bottle on top. Tape the bottle to the inside of the mug around the rim.
  4. Add distilled water to activate the project. It will begin spewing fog, which you can control by adjusting the water level.

This article was originally published in the September/October 2016 issue of Popular Science, under the title “Build a Fog Machine That Fits in a Mug.”