Small air jet project, 3d print, then add small 12V fan, 9V battery, and rocker switch. This tool is used to apply a tiny jet of air to a thermal sensor for testing air flow.
Here's a short video of this thing operating with a hot-film probe:
https://www.element14.com/community/videos/22353/l/hotfilm

Here's a blog about the project on Element14.com:
https://www.element14.com/community/community/project14/diytestequipment/blog/2017/07/21/diy-test-equipment-mini-air-jet?ICID=project14-theme-archive

https://www.element14.com/community/community/project14/diytestequipment/blog/2017/07/21/diy-test-equipment-mini-air-jet?ICID=project14-theme-archive