DIGITAL STYLUS GAUGE

I own an Ortofon DS3 (I think that is the alphanumeric designation), and the weigh pan is not magnetic, if that helps.  Pure alu is not magnetic, but best to check with a powerful magnet. Also, the important thing is the weigh pan.  The casing can be made of anything so long as the weigh pan (the platform upon which you rest the stylus tip when measuring VTF) is nonmagnetic.

I use Riverstone. It is not hard to set up - I turn it upside down to install the stylus platform.

Accuracy can be verified with the two included weights. 

That Rega has a small target to lower down onto.

It is not always easy to see the stylus tip, so I like a larger surface to lower the stylus onto, doesn't have to be perfectly centered, the downward force can actually be measured at the corner of the cartridge body, it is the same, 

Approximately 3 months ago, I met J.R. Boisclair of WAM Engineering (Wally Tools), at an audio show in a Hilton in New Jersey.

He was setting up a turntable.

He was using the Riverstone gauge.  While speaking to him, he recommended that I use the same one.

He was selling various turntable tools -- but not the Riverstone gauge.  He said that I would find it on Amazon.  So he had no profit incentive in recommending that gauge.

I purchased it, and it was simple to calibrate.

Note that it is so sensitive that, if you breath on it, it will register the weight of the wind.

Here's the one I use:

Audio Additives - Digital Stylus Force Gauge - Music Direct

I also have my old tried & true Shure SFG-2, which I've used to double-check the digital one.