None of that is necessary. I built a working electric motor in cub scouts using several feet of wire, tape, some iron nails, some sheet metal cut from tin cans, a wood board to mount it on, and a battery.
Tools required: tin snips and a hammer.
A battery can be made from a jar, lemon juice, and two electrodes.
Believe me, as an 8 year old, my skills were limited to using a hammer to mash my thumb with. :-)
Electromagnets substituted for magnets, and bearings were a dent in the sheet metal that the point of a nail sat in and turned. Simple and effective.
Once you showed this to a medieval craftsman, they could reproduce it and start improving it.
The version I built was far simpler, and used electromagnets instead of the magnets, but you can see the general idea.
I didn't design it, I don't know where the Den Mothers got the design from. But I found it fascinating, as you could see and feel how it worked.
I built several of them. One day, I got a little bolder and replaced the battery with an A/C cord. The motor buzzed loudly and burst into flames. I learned about alternating current that day :-)
