My biggest problem with homemade aeroponics systems has always been the clogging spray emitters. Somebody really had their thinking caps on when they came up with this design here. All you need is a 5 gallon bucket, an aquarium water pump, and a short section of tubing.
The pump is submersed in 1-2 gallons of nutrient solution in the bottom of the 5 gallon bucket. The tubing (or hose) has several 1/16 inch holes drilled into it. The tubing is positioned to coil around the container from bottom to top, and is plugged at the top end. You can see from the photo how the roots will be getting good coverage with the hydroponic nutrient solution. A 300 GPH aquarium pump works well for this.
The lid of the bucket will usually be cut to accommodate a 3 or 4 inch netted pot, either filled with expanded clay pellets or containing a pre-soaked rockwool block. Other media could be made to work in the netted pots. Plants may need to be hand watered until the roots begin to hang down low enough to get watered.
The biggest disadvantage to this system (the way it is pictured here) is the small nutrient reservoir size. The smaller the reservoir, the more quickly the solution will become unhealthy for the plants. In the commercial version of this design (pictured below), you can see how an additional nutrient reservoir has been added to the system below the 4 pods. To learn more about maintaining the nutrient solution in ANY hydroponic gardening system, check out my page on how to grow hydro, or get started in the right direction with my organic hydroponic feeding tips (which happen to be one of the easiest feeding plans ever).
With a little modification, the design at the top of the page can be fashioned into a larger hydroponic system. The design pictured here uses a much larger nutrient reservoir, which will help you avoid problems like nutrient deficiencies, nutrient imbalances, and constantly changing pH levels. Each container may have its own water pump, or a more powerful pump can be used to supply all four containers with nutrient solution.
By using a larger pump and a manifold to drop the pressure, you would be able to build a homemade aeroponics system of this type with 6 to 8 pods (possibly more, but I don't know for sure because I have never built one that large myself). A 1/3 horse power pump moving about 2200 GPH at a relatively low pressure of about 10 psi would be a good choice for a project of that size. As you can see from the picture above, small leaks in the plumbing would not be a big concern with this design (because the plumbing is nearly all self-contained).