This is a set of simple T-Track clamps for a CNC router (could be useful for drill presses, table saws, or anything else with a t-track clamp system).
They are made out of MDF, which is surprisingly strong, resilient, practically free, non-marring and the best part: If you plow a $75 carbide bit into it at 150IPM, the clamp gets destroyed instead of your bit! Why let $10 metal clamps destroy your expensive bits?
Designed to work with T-Track clamps systems like this one from Rockler: http://www.rockler.com/product.cfm?page=21276
They come on sale pretty regularly, so keep your eyes open. T-Track is a "standard" clamping system, so other manufacturers may offer compatible track, bolts and knobs.
The hole in the middle is for hanging on hooks! The attached DXF will make three clamps, one small, one medium, one large.
This pattern could be cut out of a number of different material thicknesses, however, I used 0.5" thick MDF, with the center polygon pocketed to a depth of 5/32". They are designed to cut easily with a 1/4" endmill, though you can use the bit of your choice.
Take the two halves, and glue together (I recommend Titebond III for MDF, it sets up STRONG and FAST). Then just slip a 1/4" hex bolt, or a special T-Track bolt, through the slot, and put one of the T-Track knobs on. Clamp away!
Don't paint, finish, or otherwise get attached to them. You WILL plow into them with your bits and cut them up. Fortunately, you can just make more!
Bonus points if you make your own knob w/ captive nut (if you do, please post it here!)