I could care less whether slaves, skilled artisans, or trained monkeys made the blocks.
I'm interested in how they machined them. :shrug
I haven't found any information on this particular site.
In fact, finding archeological images of precolumbian tools is somewhat difficult.
I'm not an archeologist, I don't think there is one on the site, though it's possible that being a geologist Velkyn might have more experience in this arena than others.
The only thing that I can do, that anybody can do for the moment till there is better evidence of this particular culture is to look at the other masters of stone carving and see how they did it. See if the techniques can be extrapolated, perhaps as a paralell development.
What I was leading to in my other posts about engineers, architects and skilled artisans is that they were clever. It is my opinion that the modular nature of their designs leads me to believe that they used forms etensively. You can see from the clamps that they were perfectly comfortable putting peices of rock together to be worked.
This explains how they were able to so cleanly match up surfaces together.
As for the interior portions of the cutouts, I will say: drills.
True, working in granite beggars the mind in terms of effort involved.
However, using drills, and a shitload of patience they could have removed most of the material on the interior cut outs to a uniform depth, and then finished the work with fine detailed hand tools, and polished off any tool marks.
If you look closely, you can see that the marks here are not machine perfect, merely, very very good. That isn't what matters though, what matters, is showing that they had drills. they were able to drill right through the rock, and apparently they were also able to carve dead accurate grooves.
If you, again go to the Egyptian archeology sites, you'll see that they had stone saws.
Here's a close up.
Notice how crisp and parallel the edges are. The quality of this work indicates that the blade was held completely steady. Apparently, cutting basalt was not so slow and arduous that extra cuts like these would have been avoided as being an unnecessary waste of time. There are several places where overcuts like these can be seen. If you find this spot, look around behind you to the north - there are several more within 30 ft. In one place you can find many vertical parallel saw cuts right next to each other.
Obviously, speculation only goes so far.
What I hope that I've done is to show that it's 'possible' in the sense that other cultures have machined stone to similar tolerances.