Step 7: Build the Exhaust Vent Fixture
Nevertheless, you want the affordability, challenge and fun of re-making this with tin cans and tupperware, read on! It's important that our design keep out the rain and wind, so we're going to use a 2nd leftover container and lid to build a rain/weather hood, with a backdraft-preventer flap made from the extra center stock we cut earlier while making the fan housing. To connect the flap with small zip-ties, drill two small holes per side in the lid and one larger hole per side in the flap and pass the zip-ties through as shown in the photos. The zip ties should pass easily through the flap, allowing it to hang and swing freely.
Note that the container bottom is going to serve as a rain hood on the outside of the window divider. Cut a rectangular portion out of one side of the container, which will face downwards, allowing air to escape. (See last several photos for detail)