The chimney pump is trying to be as low-tech as possible. It is made from simple parts readily available: a garden hose, a metal round container and a water tap.
The chimney pump is metal round container with a large chimney on top. The sun heats up the chimney. The pump is painted black to accumulate more heat. Because of the heat the air warms up and starts to rise.
The rising hot air creates a low pressure zone within the container. Outside in the well the air pressure pushes the water upwards through the garden hose. The difference between the air pressure and the low pressure zone should be larger than the weight of the water in the garden hose.
A hose with a smaller diameter might be easier or a larger chimney with a smaller diameter might create more draught.
When the container is filled you can open the tap to get the water.