i'm making something similar in your situation. i work at an aluminum metal extrusion company, and i am able to make stuff when i get free time. this piece of metal has 3 layers in it so i can drill a hole through the layers. put a wall on the first and second layer, cap the ends off by welding them in to make sure its watertight. now all i have to do is get some hose attachments fitted on. i finished prepping the mini fridge already. i failed the last 2 times, by drilling in through the side of the fridges when i should have just went through the door at the very beginning