Make water wheel with hinges Could I make little 'doors' in the water wheel that rotate with the wheel itself, but can also rotate around their own hinge?
First set up your doors with the origin on the hinge edge, or us an empty. See this question for more info How do I create a hinged door?
Next Parent the little doors to the main water wheel.


In the above gif I have added an empty that is also parented to the water wheel. That empty is used to control the rotation of all the doors with a Copy Rotation constraint on each of the doors.