Once upon a time, I also tried unsuccessfully to transfer color copies
to polymer clay.

The problem is that the ink in color copies does not fuse to the clay
as toner does. The methods that I have learned for using color copies
really amount to baking the copy with the paper on and then rubbing
the paper off, leaving just the ink on the clay.
With color copies, you cannot take the copy off before baking; the ink
just doesn't "take" that way.

I've tried it a few times, also with poor results. I've seen beautiful
copies using this method so I think it's just a matter of practice to
get it right.

--- Irwin

P.S. Please visit my site - walkenfeld.com - and follow the link to my
photo album. New work includes "Games," "Name Plates," and some items
in "Mixed Media."