Wiggler

[Crusty]

They're easy to use. Just start one slowly spinning in a spindle with the nut just tight enough that it doesn't go into helicopter mode and then take an object softer than the wiggler and push on it and you'll see the circles get smaller and smaller until the wiggler only spins in place and you're there. When coming up to the edge of a piece as soon as it skitters away from stationary you're there once again.