The beauty of making your own is that you can customize it however you want. You can use 5-gallon buckets to house one plant, or an 18-gallon Rubbermaid storage bin for up to four large tomato or pepper plants. No matter what you use, the basic concept is the same.
The top section will be where your soil, fertilizer and plants go. Beneath that, you will need an aeration screen, which will usually be the lid of your container cut down to fit and drilled with several holes for aeration. Use lengths of PVC, a pond basket or some other solid support to hold the aeration screen in place.
Below the aeration screen is where the water will go. You need a fill pipe that goes up through the screen so you can pour water down into the bottom. You will also need to drill a drain hole right below the aeration screen so that you don’t overfill.
Lastly, you need a mulch cover, which can be a plastic garbage bag with holes cut for the plants to come through. This needs to be held down tight over the plants to prevent moisture loss. The tutorial in the link below will give you step by step instructions for creating one out of various container types.
Building your own self watering container will save you money and give you the versatility of choosing your size to fit specific areas or plant types.