A second possibility is a decal produced with a special printer using patent-protected ceramic toners. The biggest advantage is that small runs are inexpensive and fast compared to old-school silk-screen technologies. It is even possible to order just one sheet with your own artwork. The disadvantage is that this layer of colour is not as thick as the silk-screened transfers. Also, in my opinion the colours are less vivid. It is possible to combine the two different types of decals on your metalclay work.
www.instardecals.com has a service for digital printing.