I am suffering through a very nasty cold and my wife (who is also my doctor and my nurse) strictly declared my workshop to be off limits until next week at the least. So all I can do is planning and researching. One of the things that people have suggested to me is to build a replica of a weapon that was briefly introduced in the "Hobbit" films by Jackson. In fact only a few frames have been shown so far. It is a four armed ballista firing long spears from a tower. It seems entirely plausible that this will indeed work, although some parts are a mystery. I am quite certain that the draw force must require some kind of winch or pulley system. The arrow is long and looks like solid steel or iron. The draw weight must certainly be upwards of 200 kg, especially as the power stroke is not even half as long as the arrow itself. But there is no hint of a winch or pulley system in the pictures. Also it seems like there is a sled that is used to cock and also push forward the projectile. That is critical as the sled no doubts is very heavy and will have to be decelerated at the end of the motion. As my rocket shooter proved once again, even if you employ thick wood and rubber blocks, it is only a question of time until things break apart from the relentless impacts. Therefore I think I will have to make some changes to the original movie prop. - longer "barrel" - shorter "limbs" (rubber adaption) - the sled will be used for the cocking only, but won't push the arrow forward (the string only will do that) - the arrow will be guided with a top rail for safety - a winch will pull back the lock/trigger assembly Will start to draw some sketches soon. Hope to be better next week so I can start the work.