A few years ago, my Mom got me three Earth Boxes (https://earthbox.com/). I really like them. I've tried a number of ways to grow vegetables, particularly tomatoes. Some years the tomatoes have worked out to cost about $100 per tomato :-P

Earth Boxes are the best planter I've tried. They've worked well during summers where we had droughts and super cold soggy summers. One complaint I have about them is that they're a little smaller than I'd like. Some of the bits and bobs of one of them got lost between seasons, so I was at really reduced growing capacity. I figured I'd get some more, but as good as they are, they seem way over priced to me. I figured I could probably come up with something on my own for a fraction of the cost.

This was a super easy project and I was able to knock out two of them in one afternoon including shopping for the materials. I probably could have even gotten three of them done if I had bought another storage crate and it hadn't been threatening rain. The picture shows my two old Earth Boxes in the back and the three DIY versions I made in the front.

Step 1: Tools and Materials

Tools:

Tape Measure
Some kind of snips - diagonal, oval head, tin snips, etc. You might be able to get away with scissors, but I think those will be a little under powered
Magic marker or Sharpie
Saw - I used my powered miter saw because it was fast, but a hacksaw would work as well
Drill - I also used my drill press for convenience, but you could make due with just a hand drill
11/64" drill bit - the size doesn't entirely matter so long as it's big enough for the zip ties to fit through
7/8" drill bit - I used a Forstner bit, but you could probably use anything that was between 3/4" - 1".
Scissors
Dog - optional

Materials:

I found everything I needed for this at Home Depot (Okay, where's my check Home Depot?!). You could probably find these at any big box store or hardware store. This list of materials will be enough to make three DIY Earth Boxes.

(3) 17 gallon storage tote (http://www.homedepot.com/p/HDX-17-Gal-Storage-Tote-in-Black-HDX17GONLINE-6/205808350)
(1) eggcrate florescent light diffuser (http://www.homedepot.com/p/Lithonia-Lighting-White-Eggcrate-T12-Troffer-Replacement-Diffuser-L2GT-PLTS-R5/100579509)
(1) 1 1/2" x 10' PVC pipe
4" cable/zip ties
(2) bags of gravel - I used the cheapest I could find that wouldn't fall through the diffuser
(3) 1.5 cubic feet soil
string or twine
(2-3) black garbage bags - In the past I've used standard ones and they worked fine. This time I used super durable contractor garbage bags. Unfortunately, they only came in a ridiculously large number per box. Well... you can always use trash bags.
Plants (duh)

The bins came with lids, but I didn't bother getting them. If you were planning on putting the planter on a deck or other surface you wanted protected, you could use the lid under it.

Cost of Materials Compared with Earth Box:

Let's see haw we did in comparison with the Earth Box. I'm not going to include the cost of tools or the cost of the gravel, soil, and plants, since you would need to buy those separately with the Earth Box as well.

Pipe: $5.57
Diffuser: $12.97
Crate: $8.97 x 3 = $26.91
Cable ties: $5.00 (for 100!)
Trash bags: $8.97*

Total: $59.42 for three, or $19.80 for each.

In other words, You can make three of these for only slightly more than a single Earth Box, and these are a bit bigger too.

* Note, I went with some fairly expensive trash bags, but they can easily be found more cheaply. This was the cost of a regular box of trash bags. You might even have some kicking around the house already.

Step 2: Sizing the Diffuser

When I was making my purchases, it looked like I could get one diffuser to kind of fit one storage crate, but it would be a little on the small side. That was why I only bought two crates. Of course, I was comparing it to the top area of the crate and these crates taper inward as you go to the bottom. I was delighted to find that instead, the diffuser was big enough to fit three crates perfectly. I only wish I had purchased three crates in the first go.
The Earth Boxes have their grating at about 2 1/2" from the bottom. I measured the width of the crate at this point to be approximately 14 inches. The length (on the diffuser this would be the width) was perfect as it was!

To cut the diffuser, I used a pair of snips which easily powered right through the plastic. Best to cut it a bit wide to start and close in on the actual width (there's enough length to the diffuser that you don't need to be super conservative).

Once I cut the diffuser to the right width, I cut a five by five square out of one corner. I did this because the Earth Box also has a similarly sized square in one corner of their grating. I suspect that this is for some soil to get into the reservoir and act as a wick for the water into the soil.

Step 3: Diffuser Supports

The diffuser at this point sat very nicely two and a half inches above the bottom of the crate. I suspected that once I added gravel, soil, and plants above it, that it might collapse into the reservoir. To prevent that, I took the PVC pipe and cut three 2 1/2" lengths and one 2 3/4" length. The longer one was due to the fact that this particular style of crate had raised sections while the center was about a quarter inch below these sections. Note: you may want to cut an extra 2 1/2" length to put next to the fill pipe. Two of my boxes were fine, but the third collapsed in a bit by the pipe. Rather than measure all of the lengths, I just measured 2 1/2" inches on the first one, and used it as a guide to measure the rest. It's a little trick that prevents measuring errors.

Once I got all these lengths of pipe cut, I decided I wanted to secure them to the diffuser. This may not have been necessary, but I didn't want them shifting around. To anchor the diffuser supports, I drilled two holes near one end of the pipes on opposite sides. I then put all the supports where I wanted them and laid the diffuser on top. Then, I used the magic marker to mark the plastic on the diffuser approximately where the holes were.

At this point, I pulled the diffuser and supports out of the crate, got out the cable or zip ties, fed the ties through the drill holes, and then used the marks I made to figure out where to zip tie the supports to the diffuser. You could trim the excess off of the zip ties if you want, but I figured the plants won't care one way or the other.

The last bit to do is to drill a hole in the side of the container just below the grating. This will prevent you from over filling the reservoir and drowning your plants.

Step 4: Water Feed Pipe

I took a length of the 1 1/2" PVC and, using my magic marker, traced around its perimeter where I wanted to locate the water feed pipe. Next, I used my snips and cut a hole in the diffuser for the pipe. Since I wanted this to be a snug fit, I started off conservatively, and then worked my way out while testing the fit.

Now I moved on to the water pipe itself. I measured a 13" length of PVC. I determined this length by measuring from the bottom of the crate to a height that would leave a couple inches above the lip of the container. Then I cut the pipe to length with my miter saw. Again the miter saw is fast and convenient, but a hacksaw will work with a little patience.

Next, I drilled four holes near the bottom of the pipe. The idea here is to allow the water to flow easily out into the reservoir. I used a 7/8" Forstner bit with my drill press and a V shaped block I use for drilling into round objects. This certainly made it easy, but you could probably achieve a good result with a hand drill and a spade bit between 3/4" and 1". Remember, this is getting buried, so it only has to be functional, not pretty. If you do use a hand drill, however, make sure the pipe is well secured when drilling since you could get injured otherwise.

Finally, I pushed the pipe through the hole I made earlier, completing the reservoir. My dog, Obi, inspected my work and seems to approve.

Step 5: Add Gravel, Soil, and Plants

Now that the reservoir is completed, we get to the rather prosaic bit about adding the gravel, soil, and plants. First, I added about a one inch layer of gravel on the diffuser everywhere except around the corner that I cut a section out. Don't worry if a little gravel falls through the grating. The idea behind this is to keep the soil from falling through the grating and spoiling the reservoir that we just worked so hard on (well not all that hard, but you know what I mean).

Then, I filled the rest of the crate with soil (I got the pre-fertilized garden soil) up to the height that the bottom of the plants would be. Then I added the plants. I finished by filling up the crate the rest of the way with soil until I got to the top of the plant bases.

Step 6: Cover

This is what Earth Box calls the "mulch layer". I call it a "garbage bag". In my original Earth Boxes, their fancy cover only lasted for two seasons. You can buy replacement covers, but since then I've been using black garbage bags. They work great.

The first thing to do is trim the bottom off of the trash bag right above the seam. Then I cut the bag along the seam on one side. Now you should be able to open the bag up and have a flat sheet of plastic. Depending on the size of your garbage bag, you may be able to get either one or two covers. Mine were big enough to get two, so I cut the bag again along the seam in the middle.

Now I laid the garbage bag over the planter. I felt for the pipe under the garbage bag and cut a hole in the plastic so that I could slip the pipe up through the bag. I then felt under the plastic to determine where the plants were. Where there was a plant, I cut an X in the garbage bag and gently fed the plant through the cut.

BONUS INSTRUCTABLE: HOW TO TIE A TRUCKER'S HITCH

A trucker's hitch is a great knot for getting a lot of tension on a rope or string, so it's perfect for tying the garbage bag to the planter. First you make a slip knot on one end of the string - make a loop in the string, then pull another loop through the first loop and pull tight. Feed the other end of the string through the loop in the slip knot. Now pull the end you pulled through the slip knot loop tight. You should be able to get it quite tight. To finish off the knot, tie two half hitches... aka two overhand knots in a row.

NOW BACK TO YOUR REGULARLY SCHEDULED INSTRUCTABLE

To finish this off, trim the excess garbage bag from the sides to make it look neater... or don't, I won't judge. Make sure you leave at least an inch of the garbage bag below the string so that the wind doesn't pull it loose.

Update:
My Mom says she uses bungee cords to attach her covers, so that's another option

Step 7: Final Steps

Pro-Tip: Move the planter where you want it before filling the reservoir. Once you fill it with water, it will be rather heavy and difficult to move. Now get your hose, put it into the fill pipe and fill it with water until water starts coming out the drain hole.

That's pretty much it. Check the reservoir about once a week and refill it if necessary. Between the cover and the reservoir, the planter won't lose too much water even when its hot or during drought conditions. You can also use the fill tube to drop in a spoonful of plant food from time to time.

That's it, all you have to do now is sit back and wait for your plants to grow.