Kinda like @aprilsimnel‘s and @SaturatedBrain except it records dreams so you can play it back like watching a movie. I had a great astral projection type dream once and would love to replay that one over and over.
My other device would be a cell phone hearing impaired people can actually hear on. Oh and one more for us hearing impaired, a bracelet/watch that vibrates so we can get up on time since we can’t hear an alarm clock. anyone who creates this one, I want first dibbs on it, buyer, co-owner, whatever :-)