Umm, you are twisting two strands of 16ga wire?

That wire is plated copper!
They don't use copper for springs for a very good reason: it's too soft!

I didn't realize what it was you were using at first.

While your springs will work fine for a while, I predict they will open up and lose their springiness over time, perhaps a short time.

If they are working for you that's cool, but I question how long they will last.

I'm not trying to be a wet blanket here. I just want you to be aware.
If you're going to sell these things, you'd better be sure to test them extensively before making any claims.

EDIT
far from pooh-poohing them, I'm gonna make one and try it out.