This design is hundreds, maybe thousands of years old. It is quite efficient and once you establish a rhythm it is less tiring than you would expect. It is valved so that you get airflow on the push and the pull stroke. Kind of like circular breathing. This is the design sword smiths use for all of their work, including welding during folding. It will supply enough air to heat large cross sections of metal. The key is to make everything slide smoothly so that you do not have to overcome friction as well as air pressure.
The one shown in the pictures is my portable box. It is not as well made as the one I had in my shop previously. But it will give you the idea.