A practice piece? Jesus! This is majorly accomplished and fantastic sno. You should "practice" more often. I can do a search for where your other scratchboard are, but I think Drawing is most appropriate for this, IMO. In fact, I'll add "scratchboard" in the description for the forum. Maybe you posted it in Creativity forum.
I still have a couple of scratchboards that I have still never played with. Maybe I was scared to mess with them, but I like etching, linocut, and knife work, so it seems like it would lend itself to something I'd be into. I don't know why I haven't tried it. Intimidation.