Some ideas:
Maybe look at a cooler first since it would be a lot less work than laying up one from scratch. I use an Igloo Marine Cooler with the lid removed. I made a lid out of clear plastic cutting board and it sits on the internal ridge where the ice bucket would sit. I use the hinges from the original lid for this plastic lid. Its much easier to open and close than the original cooler lid. Another handy material is white cutting boards ("marine lumber"). I buy them in cheap 3 packs and cut them up for all sorts of uses.
I prefer my inlet low so the nozzle is below the tank water (quieter). The outlet is then higher. Be aware, if you do it this way and then shut the pump off, the water will drain out. The battery and PWM sits in the Tupperware container.
Pete
