From a bunch of bad ideas, I came up with the flying tray. It's based on drone technology, and can (hopefully) carry some light stuff, like pills or medicine for elderly with movement disabilities. Make automated flight and add timer and it can fly to the target and poke around("hey, time to take your pills"). Or a super awesome party trick, as a slowly(but hopefully steadily) approaching shots or snacks tray. If it works well, why not use it in restaurants for coolness factor("one moment, your salad is flying to the table").

It is controlled by mobile phone or tablet, and can have follow mode(tracking the phone), automatic mode with preprogrammed flight path, or manual drive.

It should have some sensors, so it can smartly avoid some obstacles in follow or automatic modes.