Starting from scratch it would take about one month to build this organ assuming you still have to work for a living. All the parts are available at common home improvement centers except for the drapery blackout material found in fabric stores. It can be built using power tools found in most woodworking shops.
Obviously I cannot include detailed instructions for the entire organ here because it is a 250 page book. However I would like to give some very basic instructions on how to build the whistles and then you can decide if you want to look deeper into the project.
You can use just about any kind of wood that you have laying around as long as it is clear and solid. I used plain carpenters glue for everything. The basic layout of the whistle is shown below.
The dimensions for each whistle are also given.
The two longest whistles are bent as shown to fit onto the backside of the mounting panel. Windows are cut into the panel to allow the sound to come out the front.
The whistles are tuned using about 5 - 6 water column inches of pressure. A diagram of a homemade Manometer used to measure the water column inches is shown below.The whistles are almost a complete chromatic scale so you might be able to find another novel use for them.
Of course It would be nice to have a lot more detail on whistle construction but maybe this will be enough to get you started.