For my powder bed printer, I find it useful to have an on-board visualization system of the model that has been rendered under the powder.
(duplicate thread is on RepRap forums – check there for the FDM perspective on this: http://forums.reprap.org/read.php?2,453570 )
I think this might be generally useful. I used the Adafruit ST7735 for my project, but the codebase should be readily adaptable to any full color TFT.
Time lapse video of the visualization system running:
And before you ask, yes, that is a 3D projection with Z shading on an Arduino Mega 2560.
GitHub link to primary code checking: (GPLv2)