Ok, today I have a two-for-one special: Two builders who have both recently created Lego keyboards. First up, is Jason Allemann (aka True Dimensions) who created this disembodied pianist's hand, and then used some Technic witchcraft to animate it! He even created a nice video to demonstrate how it all works. The way he imparts the keys with realistic action is particularly neat.
Next, we have this very jolly 1:1 scale retro synthesizer, created by Master Shifu Leo J (aka, erm, Master Shifu Leo J) as part of the "Life Size Object" round of the MocOlmypics challenge. I'm a huge synth nut, so I don't even care that this isn't actually a recreation of any specific model of synth!