Dual colour / material dice modeled in Solid Edge ST7 and 3D printed on my MakerBot Replicator 2x.

Print directly using the x3g file or place the 2 stl files in separately and move and scale together as one.
Remember to select the 2 separate objects colours if you want a dual extruded part.
The image displays a dice printed at 0.2mm resolution with Standard temperature settings and standard speed settings.