When evaluating plastic toy pianos, prioritize ABS plastic material for its high impact resistance and non-toxic properties. Ensure the sound chip quality provides clear, non-distorted tones with a decibel limit below 85dB to protect children's hearing. Key features should include multi-functional modes (record/play, instrument tones, and demo songs) and responsive keys that do not stick. For electronic models, verify battery compartment security, which must be fastened with screws to prevent child access.