Rendered with a humble Pilot Precise 5 pen. Those are great for sketches. I like the bite of the line work here. I wonder if I can duplicate it in a more finished product. The challenge is to not tighten up, but respond to the line you are putting down. I’ll be using different tools — a couple of Hunt crow quills — so the line will feel different. But those quills have plenty of teeth. We’ll see.