This is a quick cheap and easy way to get some practice at producing your own food. Aquaponics is great because it lets you grow healthy fish and plants faster than normal and with little maintenance.
My reason for building this project was to get practice and learn about any problems that will come up before making a bigger system.

Step 1: Get Materials

Materials:
-Steel cart and some steel bars
-Plastic bins that cover about the same area as the cart
-Larger, deep plastic bin
-Water pump with a roll of tube that fits it
-Bag of pea gravel
-Plastic colander
-Scrap plywood
-Gallon milk jug
-Whatever type of fish and plants you will want

Tools:
-Welder
-Hot glue gun
-Water proof glue
-Knife or scissors
-Shovel

Step 2: Make the Skeleton

Make it look like the picture. Your pieces will be different than mine so I'm not going to write out specific lengths and sizes.

Once the frame is made cut and attach the milk container. Cut across the handle, cut a big opening in the handle side, and cut a small opening near the top of the other side. This will be a funnel for the water coming out of the grow beds. Attach it to the frame with a zip tie through the handle and around the steel bar.

Lay the plywood pieces on the horizontal steel bars. These will support the cat litter boxes.

Step 3: Make the Grow Beds

Drill a hole about 1/2" to 1" in diameter in the lower corner of both grow beds. Make sure you do the opposite corner on each one so both of the beds can drain into the funnel.

Cut the plastic colander into fourths. Glue 1/4 of it over each of the two holes in the grow beds to keep the gravel from flowing out the hole. You don't need the rest of the colander.

Support the back of the drain funnel with zip ties from the corners of the grow beds.

Wash the pea gravel with water and put it in the grow beds. Then rinse it more until the water coming out is clear.

Step 4: Add the Fish Tank Stuff

Center the fish bucket on the lower part of the cart and tie it on.

Cut three pieces of hose: one to go from the pump up to the grow beds, and two to branch out into the beds. Drill a hole every couple inches on the two branching out hoses, and plug one end of each of them with hot glue. Connect all the hoses with the t-fitting and plug the pump on to the end of it's hose. If you pump can't lift the water high enough, shorten the hose as much as possible.

Zip-tie the air pump on to the cart somewhere. Tape a rock to the end of the air hose for an anchor and drop it into the fish tank.

Step 5: Put in the Plants and Fish

Decide what type of plants you want to grow. I just took what was available, dandelions, blackberry, and raspberry plants from the yard. Dig them up, clean the dirt off of the roots, and put them in the pea gravel.

Get a few fish. Mine are largemouth bass from a nearby lake. I made this choice because they are easy to catch. The main problem with these is that they jump out, so you need some type of a screen to put over the tank if you use them. I originally wanted to use perch or bluegill but the perch weren't biting and the bluegill were at a lake 20 minutes away. Make sure the aerator is on before you put in the fish so they don't die.

Step 6: Update + What I Learned

What I learned:

-A lot of the plants die after being transplanted into the system. Smaller, less established plants seem to do better. If they survive the transplantation they do very well. Make sure they get plenty of light, and keep the pump on. That helps a lot.

-The fish don't like to eat at first and are very picky about what they are fed. But after a week or two they eat better and will agressively take chunks of worm. A food source for the fish is one of the big things that needs to be worked out ahead of time, which I didn't do.

-The pea gravel must already have lots of bacteria because the fish didn't die from ammonia like some people thought they would.

-The fish love hiding spots and shade. They pack in so tight that it is hard to tell if they are all still in there. They also love to transcend their world and enter the relm of men (jump out of the water). So put a screen or lid of some kind on the tank to keep them in. I think each fish will only do this once though because they haven't done it since the first couple days.

-The whole thing seems very easy so far. Anyone can do it.