I'm working on this blueprint, here's a screenshot of the progress so far:
The creator makes it easy to package themes into the .pigment format, it doesn't help make the themes in themselves.
Expect a release soon!
EDIT: a nasty bug has halted progress on the creator, if you think you can help, please post on the forums thread.
EDIT2: seems like nobody else is getting the bug, so I went ahead and published Epidermis 0.2.