I have printed two of them, one that fits in my mobile toolbox, the other in the drawer of my workbench.
That way, those guides are always where I expect them to be, I know exactly how to position them on my work piece even without looking at them because they are always presented to my hand in the same way….
Dovetail guides themselves can be found at : https://kmtools.com/collections/dovetail
The author hasn't provided the model origin yet.