Aim: Separate the 5 parts then put them back together
Difficulty: ++
Solved: yes
Solution: See the CAST Spiral solution (WARNING, by looking the solution you’ll loose all the fun and pride that self-solving it always brings!)
Aim: balance all the 6 silver nails only on the head of the gold one.
Difficulty: +++
Solved: yes
Solution: See the Balancing Act nails solution (WARNING, by looking the solution you’ll loose all the fun and pride that self-solving it always brings!)

Aim: free the pieces from the ball then put them back.
Difficulty: ++
Solved: yes
Solution: coming (ask in a comment to have it in high priority)
Aim: move the tower from one stick to the other following these rules:
Difficulty: + (if you have a good logical brain) to +++
Tip: Towers of Hanoi can always be solved, whatever the number of plates.
Solved: yes
Aim: after mixing the colour balls, they must be set back in 4 “O”s of identical colours. The balls rotate inside their “O” and the wooden structure is in 3 pieces that can rotate.
Difficulty: ++
Solved: yes
Aim: free the ball from its cage then put it back.
Difficulty: ++
Solved: yes
Solution: coming (ask in a comment to have it in high priority)