Well, I'm doing the couching by hand. The metallic thread is pretty stiff so it's coming out okay. I'd like perfection but not being perfect is okay. I've got 3 strings done..... 3 to go.
And, I've learned a lot about how to do this if I decide to make another one. I figure my son will want one. For example, if I put my needle into the fabric directly across from where the needle came out, it doesn't hold the 'string' threads as well. Instead, I've been doing just the opposite. I put the needle in about 1/4" from the last stitch and put the needle back out across from that stitch. I'm sure my explanation is as clear as mud.