Well, Dane, It's the kind of thing I would make if I could. My wife is a weaver , and I learned to weave and spin proably 50 or more years ago. The nails will be no problem. My Email is on my profile, and you canjust send me your address there. I have made perhaps 500 nails in a day when I was young. Of course, thosue were all simple nails for a restoration, but the nails ae not an imposisiton, but arre a pleasure for me to particiape in your project. I have seen ballista projectile points, and I sort of remember them to be like a bodkin point for a longbow or crossbow bolt. I think the one I saw was quite corroded and impbeded in a human vertabrae!
As I asaid, I am recperating from surgery, and I have some time important work I need to do when I get back to work, hopefully next week, but I can get them made in the next several weeks I am sure. The only drawings I currently have of ballistas are in a reprint of a 1900 book, and Payne-Gallwey often mae things look as he thought they should. I see in a different thread that some arre worried about bodkin sockets opening up if the shaft does not fit perfectly. I assume the traditional method, and one that has worked for me, is simply to shape the wood as close as possible, then heat the shocket ehough to burn it to a close fit and mount with whatever adhesive was common at the time, probably either a pitch, gum, or asphaltum base adhesive.