/diy/ - Do It Yourself

Can any of you guys help me design a 2.4GHz wifi yagi with as high a gain as reasonably possible? I was following this guide:
https://3g-aerial.biz/en/online-calculations/antenna-calculations/dl6wu-yagi-uda-antenna-online-calculator
But I'm not too sure on the construction. From what I read, it's best to have the elements themselves quite thin compared to the wavelength (3mm is probably too thick), but doing so while being sufficiently strong seems difficult if I'm just using wires/rods held by a boom. Making the antenna on a single-sided home-etched PCB is something I'm definitely looking into, and I bought some SMA connectors for that purpose, but I'm not sure how I'd tune it properly. It would probably be easier to just get a sheet of plastic or plywood and cable-tie wires to it, that way I can easily adjust the length of each element.

The other thing I'm not sure about is the coax balun shown in this guide. Is it necessary, considering the antenna will be mounted maybe a few cm away from a grounded metal rod? What if it's mounted on an insulating rod? Will such a quarter-wave delay work with a wifi signal?

I'm assuming the impedance of the system before my antenna (a modified cheap wifi extender) is all 50Ω, but I can't say that for sure. There used to be PCB-mounted F antennas soldered directly on, which I removed, then I swapped the position of a passive to point instead to the vacant footprint of a U.FL connector, which I have simple antennas on now. The signal seems reasonably reliable, but without a VNA I've no way of knowing how well it's actually matched. Maybe I should wind an air-core transformer and test running antennas at different turns ratios? My shitty RTL-SDR can't see past 1.7GHz so any estimation at signal power is going to be just through connecting to it.