Whenever you build a thing, you have a choice to make: use pricey—but generally well-made—manufactured parts, or go the DIY route and build your own. Drones are no different, and you can easily spend hundreds of dollars on a nice frame, motors, ESCs (electronic speed controllers), and flight controller. Or, you can do go the complete opposite direction like Redditor IronMew and build a frame out of zip ties.
Yes, you read that correctly: zip ties. IronMew constructed the entire structure of the quadrotor drone from just a handful of zip ties and glue. They started with four small, cheap, brushed DC motors and zip tied them together into a square shape. Each segment of that square is composed of two zip ties that have been glued together for rigidity.
Unlike a traditional drone frame which puts the flight controller at the center of a rigid structure, IronMew chose to suspend it (also with zip ties) from the motors. That leaves just the zip ties between the motors to provide all of the strength of the quad. Once the battery and ESCs were added, it was ready to fly. As IronMew points out, it could use some PID tuning. But, otherwise it actually flies surprisingly well. Not bad considering how much less it weighs and costs compared to a traditional quad frame!