<p>There are lot of advices on the web how to paint the 3D printed objects, but generally they are advices for manual painting and this required special skills, especially if the object is small. My guess is that maybe 3D printer can lay the color layers as well? I am especially interested in the layering of enamel paints (which can be transparent and which can required high temperature heating afterwards). Medieval art has fine examples how detailed enamel art was created on the metal. Maybe something like this can be achieved with 3D printers as well?</p>
<p>If 3D priner with the paint-printing capability is not available generally then what are the prospects when such printer can be available? Maybe there are some early, experimental efforts to create such printer and maybe test devices are available?</p>

Painting Prints
Yes, you can paint your models with
enamel paints
. Actually, most paints will work. You might need to roughen the surface with sandpaper a tiny bit. Note that some spray paints might contain solvents that might soften or melt the prints, so read your ingredients!
...not with vitreous enamel
However, you can't use
proper enamel
, as that needs to be sintered after the paints have dried, and that will destroy your print unless you have used a metal-printer.
Printing Color
Now, if you want a printer to print a paste of vitreous enamel, you are looking for a
paste printer
. However, the paint for such a device needs to be very viscous, and the print quality (due to the large nozzle) will be far below what a skilled artisan can achieve. Also, you'd need one paste extruder per color.
Foils?
One could possibly work with foils, cutting them on a plotter and then carefully transferring them to the printed object. This would allow much finer details than a paste printer currently is able to create. Such a foil can also be printed upon by special printers - possibly achieving the full spectrum in a single application step.
Alternatively, one would use a "puzzle" of smaller pieces and apply each piece separately. The result might actually be somewhat similar to the
Chromolith
(Colored Stone) stonewares that had been created by Villeroy & Boch starting 1876.