In order to build rectangular planters you need two tools, and they are both tools you should have around the house anyways on your mustachian adventures: a saw of some sort (hand saw, skilsaw, chop saw, you could probably even do it with a large hack saw if you were stubborn enough and dont have a strong case of wrong tool for the jobitis. I would use a chop saw or ryoba saw (Japanese handsaw.)), and a cordless or electric screwdriver or impact driver. Go to the lumber yard and get 2x10 or 2x12 garden grade cedar or redwood. If you can't find these, douglas fir will work. You might even be able to get them to cut it to length for you. Ask to dig through their scrap bin and get 4 ~9 1/4 or 11 1/4 or anywhere around a foot long scraps of 2x2 or 2x4 for each bed you are building, and get some 3" deck screws.
The only tricky thing about simple raised beds is that screws don't hold well in end grain (the ends of the boards). That is what the little pieces are for. This tutorial will show you how. The only things I disagree with are that I have never used the 2x4 across the bottom that they suggest, and you should be able to get scraps for free for the corner bracing.
http://www.organicgardening.com/learn-and-grow/how-to-build-a-raised-bedOne last note: if you decide to use pressure treated lumber (I don't recommend it), wash your hands after you handle it, and you probably will want to have the 2x4 brace. that stuff warps like crazy.
edited: the same method would work for on a porch if you bought an extra 2x12 for the bottom, and screwed it between the two longer sides so that it is fully hidden when you look at it from outside the box, and so that it set the width of the box. For feet, you would cut up some small scraps and screw them to the bottom of the contraption every couple of feet. You would then drill holes through that bottom board for drainage (adding a 1/2" drill bit to the list of needed tools).
If one board width is not deep enough, use two, and just double the length of the corner blocks.