Parts:

• base
• handle
• stone x 3
• pin x 3

Assembly:

• put pins in stones
• put stones into their tracks
• put handle on pins
• check if everything moves freely
• connect handle with pins, you can use glue, I used a soldering iron set to 120°C (for PLA) to squish the top of the pin on the handle. (One of them broke because the pin didn't rotate freely)