Phono Protractor. Recommendations?

http://turntablebasics.com/  $20

I’ve been using the GEO-DISC for years. It works for me!
https://www.needledoctor.com/Mobile-Fidelity-Geo-Disc

The absolute cost no object best is the SMARTractor. The next best and much easier to use and cheaper is the Feickert. For one tonearm only, the Mint.

Enlightenment/awareness, is a good thing if you want to play with audio.

https://forum.audiogon.com/discussions/vinyl-heresy-overhang-induced-distortion-is-not-that-importan...

Food for thought before you open your wallet.

Second the MoFi Geo-Disc. Of course if you want to overthink and work and sweat for it and have a thing for expensive Rube Goldberg contraptions you could do a lot better. But if you just want to know your cartridge is precisely aligned and get it over with as painlessly as possible the Geo-Disc is the way to go.

And yes as tablejockey so helpfully notes above the consensus among those with experience is alignment is nice but just nowhere near as essential as the people with the contraptions would have you believe. In other words pretty damn close is more than good enough. The Geo-Disc gets you pretty damn close about as easy and fast as possible.