Breaking object into parts I have a model of piano that I would like to 3D print. 
The model comes as one part like in a picture below:

I would like to print it in different parts like this:


Is there a way in Blender (plugin maybe) to create sort of joints (in a parts marked as red) so I can easily attach them after printing or this is something that needs to be done manually?
What format is the model in? What about quads or mesh?
Quick answer is you could boolean a big box to cut the pieces off.