I was watching this short clip about a farmer who grows giant pumpkins in NSW,
which was more of a spectacle than anything else, but he showed his technique of hand pollinating the pumpkin flowers. After a whole season of 2 flowers of zucchinis a week for 4 months and only one modest zucchini, I was pretty pissed off to learn, a fortnight after I cut them out for winter, that I could probably have hand pollinated the zuucks, and got dozens of them...
Here's the farmer
here's a good page on hand pollination - it covers the actual gender differentiation and technique well enough (having not tested the advice)- forgive and overlook the annoying anthropomorphisations of the sexual reproduction of the zucchini.
this youtube is also good and demonstrates the technique well -
I have been using this technique to good effect this year, and have some fine Lebanese zucchinis, a pumpkin, and a rogue Japanese yellow pumpkin. I will photo the latter and put it up.