This water garden is fairly inexpensive, easy to assemble, no problem to move around, and there's no digging required.
1. Cut boards. Cut 2x2s to length for the base frame, and assemble it with 3-inch deck screws (corrosion-resistant flathead screws). To prevent splitting lumber, drill countersunk pilot holes for all screws.
2. Assemble base. Crosscut 2x8s to make five 36-inch-long pieces, and place them edge to edge. Mark the last board so the overall width of the base is 36 inches, and cut to size. Put the boards face down on your work surface, center the base frame, and drive 2-1/2-inch deck screws through the base frame into the base. Then turn the base assembly over, and position it where you want the water garden. Use a level to check the base in both directions, and use tapered wood shims under the base frame to adjust it, if necessary.
3. Make boxes. Crosscut the eight 2x8 side pieces to lengths shown in the illustration, and assemble them with 3-1/2-inch deck screws into two boxes. Position the first box on the base assembly, and miter the 1x2 banding to run around its perimeter.
4. Add band. Center the banding on the joint line between the box sides and base, and fasten it with 2-inch deck screws. Make sure to drive some screws into the box sides and others into the base.
5. Add the second box. Stack the second box on top of the first, and add two more sets of banding: one straddling the joint line, and the other flush with the top of the sides. Cut a 1/2 x 1/2-inch notch at one corner to provide a neat pathway for the pump's electrical cord.
1. Cut the pond liner to a manageable size. A 66-inch square gives you a 1-1/2-inch allowance on all sides. Put the liner into the box and roughly center it.
2. You can divide the surplus into equal pleats on each side, or pleat all of it to one side. Then drive a few staples through the liner near the top of each side. Use heavy scissors or a utility knife to trim the liner flush with the top of the sides.
3. Position the pump inside the box, and route its cord through the notch. Cut the 2x4 cap strips to sizes shown in illustration, and screw them into place. Double-check the completed box's location (full sun is best) and level before filling it with water. You won't be able to move the box without draining it; the water alone weighs almost 600 pounds.