Slightly related, but Antikythera mechanism was build ~150BC and has a lot of advanced construction steps. If you have a few hour to go down the rabbit hole I recommend the Clickspring reconstruction serie https://www.youtube.com/playlist?list=PLZioPDnFPNsHnyxfygxA0...

Perhaps someone can ask the guy to build a "roman" steam engine.

It’s not so much about using only Roman technology to build a steam engine directly. The more interesting question is: what’s the smallest set of tools the Romans could have made that would let them build a basic working steam engine?