UPDATE: I assumed from the photo that it is articulating. Actually, not sure if it is. It may be stationary.
I saw a post about the ekich (sp?) bobbin.
Jay Smit at jvice.com is machining a very interesting bobbin. He makes the jvice, which I think is about the best tying vise on the market. I don't think the bobbin is ready for sale yet, but it won't be long.
This is a photo of it on his web site. I believe it is considerably cheaper than the other one mentioned in the other post. Don't think it takes up slack thread though.
Thanks,
Byron