That's absolutely superb Mike! Well done You might want to keep us updated on that one in the Craft/Making area.
I've yet to try my hand at making a Kuksa.
Stu, I've just found a recent photo of my kuksa, I've cropped in a lot on it so apologies if the quality is poor, but see the difference in colour between the outside and the inside! It was the same colour at one point, click on the image below:
lol it's like a black-hole! And it's clean honest!