I play piano, or at least I try anyway.  A full size keyboard is great at imitating a real piano, but what a hassle carting around. Today’s idea, and yes I am filing a provisional on this one, an expandable keyboard.  Putting it simply, you would have up to 4 mini keyboards, and a way to instantly connect them together or take them apart.  They key is, no pun intended, once they were connected, there would be no uneven space between all the keys. 

The central mini keyboard would contain the central processor and underneath would house a collapsible pair of rods that would extend and support the pieces solidly and allow for wide support, as in using a typical keyboard stand.

At the airport, you would have a standard size piece of luggage, and no more obnoxious big long case. With TSA agents looking at you like you were trying to smuggle a dead body.