The most useful part of this BigAir 45 walkthrough happens before the first cut. Channing holds the vent against the container, checks the template, and shows exactly which corrugations give the mounting flange a place to land.
Start with the air path
For a simple two-vent setup, the video places one opening high and the other low at opposite corners. That gives air a route through the container instead of two openings working in the same small area. Which vent takes air in can change with wind and sun, but the high-and-low layout is a useful starting point.
Check the steel before you cut
The included paper template marks the opening, but Channing still holds the actual vent up to the wall before cutting. The outer edges need to meet the raised, outside corrugations so the flange can be fastened. A cutout shifted one corrugation over can leave the flange with nowhere to sit.
After marking and cutting, he test-fits the vent, drills through its mounting holes, and fastens it with rivets. He seals the top and bottom edges with silicone. The demonstration also points out the vent’s drain holes, which should stay clear.
Screen or no screen?
The video installs both the standard vent and the version with bug screen. The screen is a practical choice where insects are a concern; the fit and mounting method are otherwise the same. Check the instructions supplied with your exact vent before making an opening.
Watch the original full-length video or read the source post. This article is a practical summary of the spoken walkthrough; always use the instructions supplied with your exact product.