Medieval Thoughts

I was watching the history channel the other day and got inspiration of making medieval siege weapons. Ill be currently working on a Trebuchet and a Siege Tower. My process will be a low poly in Maya, taking it in Zbrush to sculpt a higher poly version for normal maps, etc. Also I will try texturing in Zbrush and Photoshop..I want to focus more on trying in Zbrush though. I know Trebuchet's are long range castle crashers that launch huge rocks and other dense objects, but you don't see many with any way to aim. For my Trebuchet I want to incorporate a rotating gear so that an army would be able to aim their fire.