Table vice for a Shapeoko 2 that has a 1" grid drilled into it's bed. The mounting points for this clamp is 3" center to center and made for #6-32 screws. They are meant to be used in pairs with an adjustable length of 3/4" on each jaw, which gives you over an inch total (why you have a 1" grid on the bed).
The main pro of this system is, if you're making a through cut on your part, you have empty space to cut into rather than cutting into your bed. The con is if you need a part less than 1" wide, you need to shim the jaws of your clamp.
Companion to 1" clamp: http://www.thingiverse.com/thing:478459
and V-Block: http://www.thingiverse.com/thing:489254

Recommend printing at around 60% infill or higher. It has been fairly humid here lately and my large flat prints have been wanting to warp and peel the tape off the print bed, so I tried adding 0.45 DIA helper discs. If you have warping issues, try that *.stl instead of the standard one. After you print them out, adding a strip of foam tape makes a very good grip. We tested cutting 1/4" ply with one very non-factory edge and the foam had enough play to still hold the workpiece in place perfectly.