Finished and cooked!
Decided to finish off colouring my travel mug today while I listened to an audio class. It was getting quite frustrating in the end - not so much the angle of the surface but the special pens that were included. The red and green flowed pretty well - but the yellow and blue seemed to alternate between applying the colour and then removing it again! So not quite as good as I would have liked - but good enough.
I finished it off in the oven as per the instructions - but I haven't put it in water yet so I hope the colour doesn't wash off!