I've put up some video and pics of an inverted cycloid pendulum that I am testing now (at mikeeverman.com). Those who have seen the previous cycloid pendulum will recognize the bob on this one.
I realized that the little rollers supporting my "rodless" pendulum could be any length, as long as the upper and lower rolling surfaces describe a cylinder.
I think it is very interesting to watch, and even though this is still a high friction approach, what leaps to mind is a clock with the face on the bottom, and the pendulum on top, seemingly all being flipped upside down, but still works!
If only accurate to a second an hour, it still would be fun to have!
I'll be putting an electromagnetic drive to it this week, but of course am planning on an all mechanical drive and movement.
I hope you enjoy this one!

