UPDATE 2015-07-03 - I tightened the tolerances slightly for a better fit. Make sure your printer is well calibrated before printing.
Here is a 3-Way Elbow that you can adjust from angles 60 degrees to 180 degrees, designed to fit 1/2" Schedule 40 PVC pipe. It's part of a series of 1/2" PVC fittings I'm designing to supplement conventional plumbing fittings.
After creating the reconfigurable 22.5 and 45 degree angle elbows ( http://www.thingiverse.com/thing:533514 ), I wondered if there was an easier way. They take a long time to print and use a lot of plastic. And then I realized I could use the pipe itself as the axle. That brought about the adjustable elbow.
Print the base twice and the nut of your choice once. The 3-way nut lets you use connector as a 3-way elbow. The 2-way nut lets you cut a small piece of pvc to use as a hinge for a 2-way elbow. If you want to use the elbow in the middle of a piece of pipe, simply use it without a nut. See pictures. Once you have the angles positioned, glue to secure.
I put the triangular holes in the pipes to help the glue dry. On the first iteration, I noticed that being air tight prohibited drying. The ledges on the top of the horizontal holes make it printable without support structures.
I will continue to add new fittings to the series and share them as a derivative of my original 3-Way Elbow. Please let me know if there is a fitting you need that I haven't created yet.
You are highly encouraged to make new derivatives. Please tag your new creations with #HalfInchPVCFittings.