OP

Quoted from BillE:

So far I have 2 designs for these, the 1st design which are being used on several machines right now uses wire that is fed to the nearest GI light into a small hole in the back of the flipper bat. The wire being used is some pretty expensive wire designed for repeated flex applications. The primary flex point in this application is right where the wire exits the hole. The key to minimizing the flex at this point is I reenforced the wire at this point and make it rigid to allow the bending motion to be applied to a nearby loop in the wire. The loop squeezes as the flipper flips so that there isn't an acute flex at the main flex point. I have had wires break and kept redesigning it and changing materials to get to where it's at now.
The wiring is definitely more the concern than the LEDs I think, the LEDs are very small and seem pretty sturdy. Have had 0 issues so far as far as they go but only time will tell.
My second design is more costly so I will wait to see how the first design pans out in the long run to go through with it, but it involves a slip ring design so that wiring becomes no issue since the wire never moves at all. These are designed to run at hundreds of rpm and reliably transfer power. Slip rings require maintenance or replacement by design but flipping a flipper I doubt any this would ever have to be done. Wiring wouldn't have to go through the shaft but rather a slot in the shaft instead then just sealed in place. There would be of course a mount needing to be made to hold the stationary half of the slip ring to the playfield underside , probably some simple kind of bracket. I have the parts here already to try and make one and maybe will mess with it more tomorrow, but so far I am very happy with the final design of the first style.
Sorry for the crappy vid , it was mms'd then uploaded, will get the original up.