A practical approach is to form it by hand around simple mandrels. Bend the main loop around a suitably sized dowel or mandrel to match the spring’s diameter, then use fine needle-nose or jeweler’s pliers to make the clasping/hooked turns at each end so they fit the shutter posts. The very last bend at the free ends can also be made with pliers rather than trying to reproduce a perfectly smooth radius. In short: use a mandrel for the loop, and pliers for the end hooks and final tweaks.