Sialia,
As always, it is terrific art. You have some wonderful work here.
Gulla brings up an interesting point about Kettle. There is some property to that particular piece of art that implies the presence of something. As I look at it, I can see something out of the corner of my eye. Left side, near the handle it seems. But if I look, then I don't see anything in particular. I can't quite figure out what is causing the effect, but it is definitely there!
As for printing, I would think a high weight high glossy photo paper would be best. Either that or glossy cardstock in a wax printer, rather than a laser printer. It is going to be difficult to have the same feel as playing cards.
As for suggestions, the eye of a bird. Or maybe an entire phoenix rising?