A rubbermaid container or stock tank seems simplest. Don't need to worry about the water pressure that way. I'm thinking I could build a frame around the tank and add an overlapping lip around the top edge to hide the sides of the tank.
I have some hardwood flooring left over from an interior project. I could skin the frame with this.
If I make it without a bottom, I could just drop it over whatever I use for a tank. Starting to sound very doable.
I appreciate the input everyone!