This collage shows the basic steps of designing a star in Minecraft, exporting it to a 3D model using the www.minecraftprint.com/ python script, coloring it in a CAD software tool and printing it on a Zprinter 650 3D printer.
The star consists of layers of plaster powder that are hardened by colored glue. The model is then fixated by dipping into superglue, hence it looks a little glazed when finished compared to the unhardened printout. The superglue also makes the colors much stronger (compare the bottom two pics). The block size is about 1,5mm in this model, and the whole star is a little thin so that it cannot absorb all of the superglue.
Note that the colors are set in the CAD software, so it does not really make a difference which block types you chose in Minecraft. Newer tools like Mineways export everything with the right textures, so you could technically design the whole thing in Minecraft directly without needing a CAD tool.
BTW, if you don't happen to have access to a 3D printer, you can send your model to a service provider like Shapeways to do the printing.