The cut nails shown are almost exactly the shape of horse shoe nails. The difference is that they are extremely hard and don't bend. Horseshoe nails are annealed and designed to be bent at extreme angles to clinch the nail and then be cut off to length with nippers. The cut nails would be as good or better and available anywhere.
As to solid iron wire, it is available at about any building supplier. It is available in the concrete section as rebar wire. It is used to wrap and tie every joint of a concrete reinforcing system. Every form worker will have a roll hanging on his belt. It is annealed to twist and pull and is easy to work with. It costs a few bucks a pound and I keep two or three rolls hanging around my shop for any quick temporary hanging, clamping or holding need.
