Miles, I alas, missed it this year, but nine members from my Legio, Legio III Cyrenaica were there. That stone throwing ballista was just finished weeks before the event by Flavius Octavius Servus (aka Fred Wojick), and we call it the Roman Atomic Cannon. It weighs thousands of pounds, and is primarily ash. he did a fantastic job.
You can't tell it from the last photo, but that is the bed of the new cart Publius Clodius Secundus (Randi Richard), Tesseraruius of the III built recently. He is the guy manning the scorpio, with the straw hat. One of the big things for us about this event was having possibly the first arrow firing catapulta mounted in a cart in nearly 2000 years in action. The scorpio you see is from the Legio XXIV.
My scorpio is coming along nicely. I'm about to start the base, and within I hope a few months, cast the washers out of bronze. That is a new skill I have to acquire for this project. I expect to start building my melting furnace in the next few weeks to a month. The nice thing about this is I can cast bronze tribolate and bibolate arrow heads, something you simply cant find at all out there as repros (echoing the difficulty you English war bow guys have with authentic bodkins and such).
I'll be using actual artifacts as the starting point for my molds. I have a nice little 100 BC bronze head here, a small one that was almost certainly not for a full sized war bow, but would make a nice target point.
Dane