Man that would be quite a puzzle to try to unravel.
With enough laborers and patience, I could envision a kind of grind-down process, using crude diamonds or another hard substance like carborundum, embedded in a metal plate that itself had first been finely ground flat.
Well, that might solve the question of how you polish small stone surfaces flat, but some of those blocks are as big as a school bus.
How do you maintain precise flatness, squareness, and dimensions over the entire exterior of an object that size, unless you have the equivalent of modern cutting and measuring tools? Its just not possible to do by hand.
Even if it were, we're talking 2.3 million multi-ton blocks you'd have to quarry, cut, dress, transport, and set in place. We wouldn't attempt such a daunting project in our time, with advanced technology, but egyptologists insist that the ancients built the whole thing within twenty years, using nothing more than copper chisels, stone pounding balls, ropes, and brute force.
Not only that, it was so easy for them, they built two more giant pyramids on the same site. And just for good measure, they carved a massive labyrinth of tunnels into the solid rock under the whole complex.
To top it all off, they didn't leave a single inscription or hieroglyph upon any of these monumental structures throughout the country, nor did they record the magnificent accomplishment of these massive constructions on any papyrus, stele, or temple wall.
Who knew the pharoahs were so modest?