This toy guitar is the most robust that I've found. No plastic in sight. Theoretically, you can lower the 4 sides agree entirely, only the top two, higher are made of wire and sound unpleasant. Practically, our little musician has all turned at once.
Our guitarist is 2 years old and plays the guitar the most, if it is at the table, because holding and games is still a little hard for him at the same time.