I really enjoyed the Flexible Hose by Sal (http://www.thingiverse.com/thing:43272). It is simple, easy to print and works great with PLA. The only problem was that I found it hard to remix the ball and socket connectors because they required hollow printing.

What I have done is replicated the Flexi-Hose ball and socket connectors as separate STL files for later merging with other adapters. I have modeled everything as hollow to begin with, so no special print settings are required. The connectors are still compatible with the original Flexible hose.

I have also included models for a nozzle and a 40mm fan adapter, besides the normal tubing joint.