Gather 1x8-inch cedar boards. (You also can use 1x10 or 1x12 boards to create a deeper pond.) Cut 30-inch lengths for the sides and 15-inch lengths for the ends.

After assembling the outer frame, measure the interior dimension for the floor of the box. You can use the same 1x8 material for the base or use 3/4-inch exterior plywood. Use a handsaw or circular saw, or have the wood cut by your local home center. Make sure you get straight cuts to minimize gapping.

Next: Make a Water Garden: Step 2