A couple of years ago I saw a TV prog on the History Channel about a team that "rebuilt" a machine of war referred to in the chronicles as the "Werwolf" - or something like that. This was a trebuchet that King John (of Robin Hood fame) had in his siege train - and, according to the medieval annals, it was blessed with almost divine powers of destruction!
Anyway, some of the things I recall if anyone wants to track the programme down. The team was composed of international craftsmen skilled in using the tools and working practices that would have been around in the Middle Ages - no electric drills, planes and suchlike! There were a lot of carpenters, ropemakers, ironworkers, stonemasons etc. All raw materials were sourced as they would have been available at that time - you need wood, chop a tree down! They had set themselves a timetable of two weeks to build it and have it operational. They also built a stone structure to use as a target. It was filmed on the banks of Loch Ness.
Long story cut short - the thing got built and the stone structure was destroyed. Mission Accomplished. Then, just for a giggle, the bossman of the Oxford Dangerous Sports Club (the inventors of Bungee jumping) turned up in top hat and tails to have a go himself, as the projectile. He survived it!