Yeah sure its free and surprisingly easy to do. There's a bunch of these on line, this one looks pretty good to me
https://www.sound-smith.com/sites/default/files/Novak%20Universal%20Overhang%20Gauge.pdfA couple tricks and things to keep in mind:
Don't try this in your listening room. Move the whole rig out onto a nice big clean and well lit table. With a comfortable chair. No long sleeves. No distractions. And give yourself plenty of time.
This protractor neglects the fact that its paper thin. Alignment should ideally be done at the same height as when playing a record. To do that, simply tape your protractor onto an old record.
Once you get the protractor pointed exactly at the tone arm pivot use a little Scotch tape to keep both the platter and the protractor from moving while you're working. This first step is really important as its what determines overhang. So eyeball real good to make sure its pointed exactly at the tone arm pivot axis and then tape it down so it doesn't move.
Mounting threaded cartridges is pretty easy. But if yours uses nuts a rubber band comes in handy to hold the cartridge on the head shell while you get it threaded.
Have tweezers handy for installing cartridge pin clips. Test first and tighten if they are loose. To tweak tighter without crushing put a round toothpick in the clip and then squeeze with pliers. The toothpick will prevent crushing it flat if you squeeze too hard.
You can lay a Q-tip crosswise just right so it supports the cartridge just slightly above the surface, and protects from damage in case you spaz out.
Cartridge alignment is only ever perfect at the two null points. So don't obsess over that last tenth of a millimeter.