If you wear glasses, the 3D movie glasses are rather uncomfortable... So make your own clip-ons!
These files will NOT fit your glasses (unless you happen to have the same frames), but here's how it was done.
Trace your glasses frame onto a piece of paper.
Scan the tracing; import into your editor of choice (in this case, inkscape)
Make sure your editor DPI matches your scan (inkscape defaults to 90dpi).
Using the path tool, trace the frame; just trace one lens, as you can mirror image it later.
Export the path to openscad.
In openscad, you'll now need to: make the cutout, mirror it, and figure out the spacing.
Print it thinly (height=1mm) with 0 extra shells, to make sure it aligns with your glasses.
Add the posts, and print it in black!
Deconstruct the 3D glasses from the theater and glue the film to your print; trim the excess after the glue dries. (If you're smart, you'll do one side at a time, and make sure the film is aligned/facing correctly.)
These might be more comfortable, but the movies may still give you a headache...