Cartridge alignment tool

Here ya go!
 https://www.needledoctor.com/Mobile-Fidelity-Geo-Disc

Dr.Feickert is the best ever to make alignment of everything. Still relatively cheap for such precision tool, top quality! 

You can not measure Pivote to Spindle distance with cheaper protractors!
Also with Feickert you can choose between Baerwald, Lofgren and Stevenson

+1 for Mint Best. I have one for my Technics 1200 tables and one for my VPI Aries. Alignment with these was worth more than any single upgrade to my vinyl playback.

Excellent protractors can be had for free and up to big $$$.  If you have multiple tonearms/turntables and swap out cartridges regularly, then it make sense to invest in a universal protractor like the Feicket.  If you have one tonearm and one cartridge, a custom protractor like the MintLP would suffice and give you an accurate alignment.  You can also go on the Conrad Hoffman website and print off a custom protractor free of charge.  There are a lot of excellent options based on one's budget, system requirements, and desire to obsess over details.  

Generally agree with brf.   

There is no uniquely best way to set the horizontal tracking angle (HTA) for a pivoted arm. This is different than azimuth and even SRA where in each case there is a best position (even if it varies by disk for SRA). Experts disagree quite a bit on what HTA rule is best. Each possible setting is a compromise. Moreover, for this reason IMO the effect of a different HTA is exaggerated by some people and I am always amused to read that someone spent hundreds and hundreds of dollars on a protractor and came up with an HTA setting that "blew me away." My own suggestion is not to obsess over this setting. 

Any of the usual tools used with care will get you to a reasonable solution.  The only advice I have is that an even inexpensive tool with a mirrored base can help avoid parallax error.