@Criggie Yes some good ideas there. Thank you.

@Criggie Any ideas on what to use to design the housing. I want to use this to assist in taking out the foul air in a bathroom as a helper to the small evacuation fan that is already in the bathroom. I have already done a test and it fan high and low speeds work and it is a pretty strong fan. I also want to use the microwave door switches as the fan switches, maybe screw the switches into a piece of wood and then turn them against another piece of wood to push the little on/off in and out.

Happy new Year all -- my state (GA) officially adopts the 2020 NEC code today... yippee...

@Bijan79 I'd go with something thin and formable. Depending on what you have for stock and tools, either some thin sheet metal or something like Kydex plastic that can be formed.

Ideally you want a smooth curve with no corners or edges.

Plywood might work but could absorb moisture, steel could rust, so paint and seal it well or use aluminium ?