Check out http://www.thingiverse.com/thing:988513 for an improved version of this capo.
No fiddling with screws and levers - this one-piece capo clips on with one hand. The presser bar is contoured for a radiused fretboard. Don't have a guitar? Print these for your friends and they'll stop laughing at you for being a geek! (Or, just print your own guitar: http://www.thingiverse.com/thing:710561)
Update: In the original STL file, the spring could break if you tried opening the capo too far. I made some minor tweaks so that the spring bottoms-out before breaking. Use this file current file capo_c.STL instead if you've downloaded an earlier version.
- Printed in PLA with 0.2mm layers, 5 shell, and 35% infill. You want this fairly solid so that the spring works properly. (ABS is not a stiff as PLA, and I'm not sure it will work for this.)
- You need very good adhesion between the perimeter lines for this to work properly. You may need to bump up the temperature, and maybe increase the extrusion multiplier parameter a little to make sure the perimeter lines fuse completely.
- I put a small felt pad on the bottom clamp to protect the finish on neck. If the clamp is not quite tight enough, you can use a thicker pad.
- Putting a rubber/vinyl pad on the presser bar can also help keep strings from buzzing. I use 2 layers of vinyl electrical tape on mine.
- Don't leave this clamped on when you aren't using it because eventually the spring will relax and not squeeze hard enough.
- I've had some people say that their capo works well in one color but not in another. The pigment can affect the strength and stiffness of the PLA, so you might try a different color if yours doesn't work well. (I suspect less heavily pigmented PLA will work best.)