I'm not certain of what tool he is using to generate the SVG files but a great option is Inkscape, which is FOSS and free-as-in-beer. If you want an illustratio

I'm not certain of what tool he is using to generate the SVG files but a great option is Inkscape, which is FOSS and free-as-in-beer. If you want an illustration tool, Inkscape is definitely the best non-Adobe option I've used (and as someone with a monthly subscription to all of the Adobe tools, probably the best option overall).