Best tool for cartridge alignment?

Hello. I am looking for an accurate cartridge alignment tool and perhaps you can help.

I have a Michell Gyro TT, Rega RB600 arm and Shelter cartridge. Which tool will work best for this set-up?

Thanks for your comments
The "best" cartridge alignment tool is probably the Wally-Tractor, which is custom-made for each particular tonearm/turntable combo. I think it costs about $150 from Wally, and takes a couple of weeks for an order to arrive.

However, the Dennesen Soundtractor (which was made in both metal and plastic versions) is very good (I have the original metal version, which I use to set up my Rega 900 tonearm and Grado Reference cartridge). I think the plastic version has recently gone back into production, but if you can find a used metal version, it's certainly worth having.

The other possibility is the Geo-Disk mat, which works pretty well and is easy to use.
I set up my Gyro/OL Silver/Beta S with a borrowed GeoDisk. They are back in production for around $50 if I recall.

Works well enough. It's easy to use but not infallible--you have to make sure a certain line on the GeoDisk lines up with the tonearm pivot point just right or every other adjustment you make will be off.

I hear great things about the Wallys but have always been deterred by the cost and lack of availability.
I second the Dennesen Soundtractor - its not only effective, it's very easy to use so long as your arm has a depressed point over the center of the shaft. I especially prefer this over systems that use two reference points.
thanks for all your suggestions and help. all three looks good to me...not sure why the wallytractor is so pricy.
I'd say the Wallytractor is so expensive because each one is made for a specific tonearm (effective length + overhang), and lovingly etched by Wally himself (mine is signed and dated). IMHO, there is NO other alignment device that gives the level of precision and accuracy of measurement that the Wally delivers, and you are able to select between both Baerwald and Loefgren alignments. I used to use a Dennesen, and the difference is not subtle. Obtaining a Wally (and having the patience to use it correctly) will be one of the best upgrades a serious analog listener can make.

The first question to ask is, what kind of alignment would you like to achieve. Baerwald? Loefgren? Rega?

Most people prefer the Baerwald two-point alignment, which produces the lowest distortion across the whole side. Unfortunately it may not be possible on a Rega arm. If your 900 is mounted at the standard Rega pivot-spindle distance (222mm) then the cartridge will have to be very near (or perhaps beyond) the end of the slots to reach the Baerwald points. OTOH, if you can move the arm closer to the spindle (219.5-220mm works well) then a Shelter is long enough from stylus-to-mounting holes to make Baerwald alignment achievable.

For a poor man's version of a Wally Tractor for Baerwald alignment, go to Their $20 printed protractor is not quite as accurate as an etched Wally, and it does require accurate aiming at the arm pivot. OTOH, it's mirrored like a Wally. This makes alignment of the cantilever MUCH easier and more accurate.