As long as there is something in the bow for the string to hit, the bow itself should be OK.
Regular dowel wood won't hold up well to multiple shots; I'd certainly take precautions such as wearing good safety glasses if you do go that route.
Personally, I recommend a good 90# spline-weight cedar shaft as a starting point to making your own. They will stand up to repeated use, but you won't be out much if you do lose one or two; especially since you can make two bolts out of each shaft.
Still, there are not many New Zealand archery suppliers (at least on the web), so you may not have much to pick from locally.