If you can find a plastic 55 gallon drum, cut it in half lengthwise (put some self tapping screws in the side of lids so it stays in place). Put 4 post in the ground using the size of the 1/2 drums to build around. Make a simple frame on your post, screw the drum halves to the frame and put a metal top on it (you might put a concrete block under the drum to support it). You can either make a long trough or two smaller ones.