I was thinking to do a loft or sweep, between two copies of the gear profile. Rotate one of them first,
to sort of match the helicalness...

Boston gear has a free book called "Gearology." Download at their site did not work, but it can be downloaded here:
http://www.beknowledge.com/archives/article/gearology-handbook-on-gears-for-mechanical-engineering

MITCalc has a free 30 day trial.

Lots of math...