In article , xyz wrote:

I want to do temporary soundproofing by making a window plug for
a 4' by 5' window, and I'd appreciate suggestions.

I'd suggest alt.energy.renewable, alt.energy.homepower, alt.solar.thermal

but you could probably buy a piece of foam (with reflective aluminum
backing) that would fit in the window for cheapo, it would be
light-weight, and easy to replace.