@Kingshark Mine is a scanned pencil drawing. Sometimes, when I feel like it, I draw a pline over it in AutoCAD and add everything else, like kerbs, runoffs, pits, marshall posts, contour lines etc. in seperate layers. But that requires a lot of time and some skill as well.
Now that you mention it, it does look a bit like Autódromo Juan y Oscar Gálvez indeed, even though my main inspirations were Suzuka, Spa and Interlagos.