A laser leveller does work but a thread (not "string", I misspoke) is actually more accurate - thanks to the parallax effect. Sometimes simplest is best. :-)
One thing we ought to have asked is, what tonearm/turntable are you planning to use this protractor with? If your rig isn't Baerwald compatible then this whole discussion is moot.
One thing we ought to have asked is, what tonearm/turntable are you planning to use this protractor with? If your rig isn't Baerwald compatible then this whole discussion is moot.