Pieces to make the golden birdcage are given as rewards for the tasks in the 'Maze Garden' area:

1. 🔓 Unlock the 'Maze Garden' area.
2. ✔️ Check the tasks for special rewards (pieces of the cage).
3. 👀 Focus on those tasks and complete them.
4. 📥 Collect the rewards from the queue in the mainboard (in between inventory and shop) and merge them.

🎯 NOTE:
Only one birdcage can be stored on an account and it can't be sold or discarded.