MenaceRC 5.8Ghz Linear Whip Antenna Tool
The Menace Antenna Tool has been designed to take the measuring and guesswork away when making your own linear whip antennas.
A little while ago Menace released their 3D printable tool as a free download on Thingiverse to help you make 5.8ghz whip antennas. After lots of requests from people without access to a 3D printer, they made a high-quality ABS 3D print you can buy along with enough coax cable to make 5 or 6 antennas.
Here is the video on how to use it: