Locking Ball Cage
thingiverse
Guess, you need two of it. Use a stealth-lock or a permalocker. Inner dimensions 40x40x50mm. Use at own risk. Print in place. Layerheight 0,2 mm. You may want to drill out the lock-opening in case you need to scale it slightly. Reinforce the joint with a piece of filament prior to cutting/breaking it free.
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