Was Steam or Electric Power used to carve these amazing shapes?

The 'Alien Coffins' of the Saqqara Serapeum

The Egyptians had steam power or at least electric power in order to carve these stones. They seem just too well done!

From the Serapeum. It seems electric tools may have been used here. OR hand carving. Some angles are 'too' precise.

Schist disc and other artefacts. Coated in Stone?

By Dr. Charles Kos.

A question which pops up now and then is how the Egyptians were able to seemingly 'make' stone. It was a Roman belief that Egyptian statues and other artefacts were 'cast'. This was mentioned by Pliny in his natural history. Stonemaking is in fact the alchemy that the Egyptians were renouned for. Here we come across the Schist Disc. In the video, I suggest this is metal which has been coated in stone. It is obviously a turntable of some sort. It also does not match the goods in the tomb of SABU, which are neolithic.

BUT, one comment on the video offers are more pragmatic solution, suggesting it is made of clay, a kind of plate for feasting. Candle holder in the middle.