[Openurmind]

I think the most probable method that has made the most sense yet that would fit into their capabilities would be the bronze edged swinging pendulum. While this points to the Mycenaeans, I think it is very possible the Egyptians may have used the same method. It would definitely be within their limited technology level yet work well.

But there are indeed some anomalies in cutting work that truly cannot be explained such as core drilling and cores uncovered that were truly part of the ancient construction at the time, same in South America.

https://www.sciencenews.org/article/how-backyard-pendulum-saw-sliced-bronze-age-mystery

[SoCal Pubbie]

This is a long read, and I did not go through all of it myself, but this guys suggests they used ultrasonic machining:

http://www.theglobaleducationproject.org/egypt/articles/cdunn-1.php

[SoCal Pubbie]

This is shorter, but not sure if covers the ultrasonic part:

http://www.theglobaleducationproject.org/egypt/articles/hrdfact1.php