If you happen to be passing through the University District, you might consider dropping in at Hardwick's. It's a hardware store located near the intersection of NE 42nd Street and Roosevelt Way. Though I would be surprised if you found your finger vise, you might be able to find the parts and materials to construct your own. Anyone who has ever been into Hardwick's knows that they are the hardware store of last resorts, as they tend to have the one thing you can't seem to find anywhere else. They're chock-a-block with some of the most amazing tools you'll ever see in one place. You'll probably need at least an hour to absorb even a quarter of what they carry there. Talk about sensory overload! Still, it's my favorite hardware store to wander around in a daze. Good luck!