I've added very small ridges at each end so it fits snug into the Flipper Zero Case Reinforced Wifi Top Strong
https://www.printables.com/model/495471-flipper-zero-case-reinforced/comments/1010406
You might need to file one end very slightly for a perfect fit.
The author remixed this model.
Now with updated STL Base file with the extended sides to provide a snug fit.