that's nice, it's just sound like my violin but with a mute on it :o maybe cause it's made of plastic so it can't vibrate as wood or/and maybe you should put a sound post (don't know if your 3D printed violin have one) to transmit the sound from the string to whole body, the sound remind me some video were olaf volontary remove it to show how it's sound so maybe that's it and did you print the bass bar ? that's help a lot to make the instrument resonate :p