This is a small mount to put a sevenswitch (http://reprap.org/wiki/SevenSwitch_1.2) on one of the threaded rods which make up the lower frame of the RepRap Prusa i3. By changing the parameters I could attach any rectangular thing with four holes in the corners to any round thing. I made the plate thickness the same as the cylinder wall thickness. I made the plate corner radius the same as the standoff radius.
I haven't found a good way to print it. I did it with the standoffs pointed down and some support, and slic3r still made some crazy bridges, which worked ok but looked ugly. I didn't try again, since the first try worked fine. I thought about using a hull to connect the cylinder to the plate, but then I wouldn't have a good place to secure machine screws underneath.
Updated 18-July-2016 to make the output stl manifold, thanks to Sir_Death for pointing out my error.
Anyway, I hope this helps someone or serves as a starting point for something useful.