what is it when they say perhaps "blueprint of an engine" or "i blueprinted the bottom of my engine"? what is blueprint towards the engine?  

Blueprinting is a proccess that goes hand-in-hand with bottom end balancing. The general gist is to peel apart the shortblock( engine block and rotating assembly) and weigh each piston and record the weights. All pistons are then filed or otherwise machined to remove material to match the lightest weight unit. This is then done to the connecting rods. The Crankshaft is usually precision spin balanced at this time(they are balanced to a much finer degree than factory spec). Piston rings are inspected and/or replaced. Cylinder bores are precision measured and honed as needed or requested.  The total result is a slightly smoother running engine and a higher total top end. This also gives the engine tuner a much clearer idea of what he has to work with. The blueprint is simply the total recorded measurments of the engine and typicaly a dyno graph of it's performance after said process is complete and engine is rebuilt.