Some thoughts:
Hally's illustration(s) could be incorporated into a mug design by someone with design talent - which might be herself, but could be anyone.
I can technically do that kind of thing - but unfortunately, I dont have any real talent in that direction (design). Actually when I think about it, I'd say some type of hand drawn/inked calligraphy would go super with these images.
One Two of the things I love about the illustrations are the hand-drawn/painted quality, and the use of an aged looking paper. (Trying to convert them to vector images would lose a lot imo.)
With an illustration like that the most important thing initially is to get a really good quality and fairly high-resolution scan (or photo).
Till now all DC/NANY mugs are printed on a brilliant white -
an off-white or ivory mug would suit these images much better I think