Summary

This business card dispenser has a snap-on lid, but there is no material at the axis of rotation, so it looks really cool. When you rotate the lid, the oval hole lines up so that you can slide out a card with your thumb. There is also a little nub that catches and holds it closed.

Video: http://youtu.be/P1VHHy6cXok

Instructions

I never bothered to figure out how to properly orient my stl files, so you'll have to flip them around in your slicer. The parts are not symmetrical, though, so if you mirror in z make sure to mirror another axis (x or y) so that the little catch mechanism that holds the lid closed ends up on the correct side.

The tolerances on the pivot mechanism are a little finicky, so I have included two "proof of concept" stl files to test it out. That way if it doesn't come out right you won't waste too much plastic. If it's not working, try lowering the print speed, make sure you're not overextruding or underextruding, etc.

I used a clamp to force the ends together, try and line up the lid and base so that there is minimum overlap of the pivot mechanism to facilitate snapping them together without breaking it. There are a total of 6 sliding contact surfaces, but in some orientations only 3 of them are touching (about 22.5 degrees from the closed position). This is how I would recommend you line it up before snapping it together.

Initially, it was quite a tight fit and didn't spin very well (I'm guessing from little blobs on the sliding surfaces, so clean them off!). After playing with it for a while (about 20 minutes) I was able to get it to spin really smoothly. Alternatively, if your proof of concept print is binding too much, take some sandpaper to the sliding surfaces (lightly) before snapping the parts together on the real thing. Once you have it worn in nicely, dab a little WD-40 on the pivot for extra silkiness.

Also, put a little rectangle of clear tape on the ramp inside of the base, otherwise the layers will grab the edge of the business cards and they won't slide out nicely.

I had some pretty significant warping at the corners, so I imagine you would get better results on this print if you have a heated bed.

Edit: I added some with ears to reduce curling without a heated bed, which work beautifully.
Edit: some people are having problems with the joint being too tight. I have added files in which I have concentrically widened the groove on the top piece.

Magic Pivot Business Card Dispenser