Now we all know that hydroponics means that the plants are grown without soil, but that they need some kind of growing medium. Aeroponics does away with the need for a growth medium, as the roots are literally suspended in the air. They get their nutrients as well as the water needed for the plant through a mist that keeps them alive and well.

Commercial aeroponic systems are rather expensive, thus many people envision building their own when they wish to venture in aeroponics. Commercial systems usually have pumps that are calibrated so that the plant receives aerating times between feeding times. Thus, in other words, the feed/aerate times are programmable. If you are to build your own, a simple timer with multiple on/off settings can duplicate this need.

Many commercial aeroponics systems also do not utilize the standard PVC piping that most use in home built systems. Instead, they use a higher grade PVC that is coated with titanium dioxide.

This suggestion is over simplified, and the results are rather primitive, but if you like the results you can build a bigger and better one in the future. By using a fountain pump, you will be able to rotate the nutrients and water into a constant feed and water time if you wish. Adding the on/off regulator suggested above should be easy. 1/2" poly tubing will carry the water and nutrients for you. You will need a few poly connectors, of course. Fogging or misting spray nozzles will do the job of misting your plants. You will also need some poly tube extenders to mist the roots higher up. Be sure and purchase hose fittings so that you can attach the tubing to the pump. You will also need approximately 12" of clear tubing and angle connectors. Ask for net cups next, and finally you will need a large heavy-duty plastic container that has a concave reinforced plastic lid. 

You'll next drill 2" holes through the lid spaced so that you do not drill through the plastic ribbing that gives it its strength. Using the net cups in the sealed "tank" you've created will enable you to utilize the aeroponic system to grow your plants.

By running the tubing and misting spray nozzles so that each plant's roots will be covered with the nutrients and water, you'll love how this works. Any runoff that congregates on the lid will run back into the plant, thereby not wasting nutrients or water. 

Aeroponics have a tremendous advantage over hydroponics, as the roots are suspended in mid air, enabling them to take advantage of both the nutrient solution as well as water, but the best part of aeroponics is that by hanging suspended in air, the roots will be able to stay oxygenated. You will not believe how quickly your plants will grow, nor how healthy they are, thus cutting out a lot of work to take care of sick plants, weeding them or just killing various bugs and such that can attack weaker plants.  Good luck!