This shows the complete setup, an aquarium pump pumps air through a column of desiccant and into the T-Adapter of the camera.
The cylinder is made from PVC components, I use Drierite desiccant, it changes color when its spent and then it must be recharged in the oven.
This shows the T-Adapter modified with a brass tube, note the filter uses in the air line to keep dust of the film.