Here is a gyroscopic trainer that helps you build strength in your upper body using centrifugal force. This portable gym is 3″ deep with its handles removed, so you can pack it into your suitcase. It only weighs 1-lb. To get started, simply grip the handles and swing the strengthener in a circular motion.
The Gyro Grip is powered by a 9-volt battery. The display shows the RPM and workout duration. You can get yours for under $100.