With the thread generator, Screw-top containers aren't quite automatic, but they're close.

This is uploaded more as an advertisement of the screw thread script-- rolling one's own containers should be pretty much a snap with it!

Note! Nophead has printed the design as it now stands and the screw-cap doesn't work! I've uploaded a new version, but until we get confirmation that the fix worked, Nophead's field-tested design is here: http://www.thingiverse.com/thing:84

Edit: Added the Blender file. This should make it even easier to scale this model to whatever size and height/diameter ratio you want!

Print it and use it! Single STL file fits in the MakerBot area, although perhaps you'd get a lot of stringing if you just printed these together like that...