Ok I am official happy with this sketch. I don't know how I did it, but it's fine with me!

Blue and white Conte crayons with the dark areas drawn with a 4B pencil on white Mead sketching paper. Scanned into Photoshop. The details added as text and a single color adjustment layer added to shift the blue to more violet. About the right color... okay about being the key word there.

Compare this to Peter Lawrence's superb image here: You have to turn his image 90 degrees CCW and mirror reverse it. I would do it and include it in the sketch but need permission first. You'll see why I am tickled with it!

Okay I just edited the image to pilfer the color from peter's image.