Chess medal inlay

Two of my sons regularly participate in chess matches.
Not at all matches they get a medal (or a cup). To stimulate them to continue with chess, we regularly give them a medal ourselves (after a match).
To make the medals more interesting I decided to make inlays from chess pieces.

I made them in OpenSCAD from the pieces of http://www.thingiverse.com/thing:585218.

So far I only made the rook.