Rollin' on the River

I was playing with the right angle triangles the other day when I came up with this:

 

 Immediately I thought of this:

Which of course in turn led to this:

I used two squares with gimbals and a strut to hang the wheel, which actually turns. You have to be careful to leave a little room between the wheel and the outside square with gimbal to give the wheel enough freedom to turn.

The back looks like this:

Here's the flat layout:

So I hear someone saying, "But I don't have squares with gimbals nor struts....." Well there's always a way to work something out. I did this one using the handle of a wooden spoon. A dowel rod would be much better.

I'll admit that it's less stable and a bit less elegant, but it works. I'm sure that you can come up with other ideas. Maybe some day I'll take the time to make a mill.