For a long time, I was against the idea of building a homemade aeroponics system for many reasons. Usually, there are expensive pumps to buy, there are always problems with clogging spray heads, and there is always the potential for a homemade water disaster until a system is tried and true. This brilliant system, designed for cloning, eliminates ALL of those concerns.
This homemade system is made from a cheap plastic storage bin, sometimes called a tote. 2 inch holes are cut in the lid to hold several 2 inch netted pots. A cheap alternative that works equally well is to use disposable 6 oz plastic cups. You need to make many holes in the cups for the roots. This resourceful guy burned the holes into the cups with a soldering iron, although you should keep in mind that plastic fumes are very toxic. Consider using a hole punch or a drill instead.
The cuttings are placed in the netted pots so a 1/2 inch sticks out the bottom, and cuttings are held in place with expanded clay pellets. The water level is kept 1 inch below the bottoms of the netted pots, which would be only a 1/2 inch below the cuttings. The clones are kept moist by an air pump on a timer.
Tiny bubbles rushing to the surface pop and throw a very fine mist of water into the air. Clones produce roots more quickly with a series of wet/dry cycles, so the air pump is set to run in cycles continuously for 15 minutes on, then 45 minutes off. Two 6 inch air stones are used to help maximize coverage. After two weeks of maintaining the water level in the reservoir (usually less), the clones should have roots.
Success with your homemade aeroponics cloner starts with cleanliness, and maintaining the right temperature. I address these two topics in some detail on my cloning success page. Start with clean, room temperature water in the reservoir. Adding a B1 supplement, like Thrive Alive B1, helps to reduce cutting shock and promote quicker and stronger root development. Always use a cloning gel when taking your cuttings. It's easy to adjust this system for rockwool. Use round rockwool plugs held in place with some expanded clay pellets in each netted pot, or simply use a square rockwool block that happens to fit into the netted pot (there are different sizes). Most importantly, keep everything as close to 72 degrees as you can.