I have a collapsible silicone bucket with a lid for popcorn making that goes into the microwave. It's easy to use, doesn't require any fat, also serves as a bowl and you can just throw it into the dishwasher. Size-wise, it's probably not that different from an air popper when collapsed, but it's easier to find a spot for; mine is on top of the stack of roughly bowl-shaped things. And you could also use it as a bowl for other things, so it's not necessarily single-purpose.