Here's a thought. Go to your local Hobby Shop and get some piano wire the diameter your spring needs to be. Then make or locate something the correct diameter shaft. Then you need an old nut that will pass over it and slot it to trap the wire's end. Now, practice winding the piano wire inside the nut, around the shaft until you're proficient, A lathe (wood or metal) or drill press will really help. Make sure you have some large Electrician's Pliers called "Sidecutters" so you can hold on to it, cut it and make sharp bends and after a bit of trial and error, you can even make simple springs for...... well, uhh, mouse traps? Seriuosly though, that's how you make a spring. Better yet, GOOGLE how to make a spring winder.... I'm a lousy explainer!
Cheers, John