The probe is made up of some 3D printed parts and uses brass tubing and washers to make the precise joints needed for an accurate pantograph. You’ll need a few other things like a camera ball head.
I have made a video showing how to build one. You can also read my blog post about the build, and you can find the various files on github.
If that seems like too much effort, just to try out the idea you might want to try building the much simpler PantoFlex.