Party tent coupling

My brother got a party tent with one coupling missing.
he knew about my Orca, so this became a challenge: for him to ask me, for me to design a replacement part :-)
I think I got it right by now, but I will only remove w.i.p. when printed successfully.
Update 2014-04-15: Added 2 layers of external support to prevent tumbling while printing. There is 2 versions now.
Openscad module also published with some comments in the code to adjust for your own measurements.

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  Thomas
  www.3daybreaker.blogspot.com