The Gyro Bowl is a spill proof bowl that uses gravity to close the lid. The bowl is a gyroscope in the form of a plastic bowl that either keeps the open side up or closes the bowl. As I’ve said many times, gravity is my favorite resource since it is always available.
We’ve had low cost plastic bowls for decades so this could have been technically and economically possible. The basic concept could be made from wood so technically it could have been made hundreds or thousands of years ago.