The biggest pain for this lil project is cutting the aluminum gutter in the parking lot to fit it in your car. You might want to bring/buy some leather gloves so you don't cut yourself. Also, remember to bring your measurements and a measuring tape. If you don't have a pair of snips, you can buy them in the store. I bought my supplies from home depot, but i'm sure lowe's or ace hardware sell gutters as well. Home depot keeps the gutter caps in boxes right beneath the gutters. Be sure to get both the left sided and right sided caps.
If you make one of your own, please post a pic. I'd love to see it.
Since I planted succulents, I figured I would just spray them a lil from time to time and not have to worry about drainage. But I got lazy and started watering them, and wasn't keeping track of how often, resulting in saturated roots and very unhappy plants.
If you make this planter, I'd recommend following @jessbruder's improvement by layering some gravel at the bottom, before adding dirt and drilling a hole at the bottom of one of the sides to attach a hose for drainage.