Through-the-wall air conditioner covers

I'm in upstate New York, and definately would like to get a more effective way to cover through-the-wall air conditioners covered for the wintertime, than those wrapped covers I've used in the past.
I've seen some houses with the air conditioners that are covered with what appears to be a box, painted to match the siding. I've brought them up with my GC/carpenter, and I'd like something like that once he gets my new siding up.
They *look like* they're PT plywood, maybe pressfit on. My GC and I were talking about maybe sizing them to press-fit, with board insulation on the inside, and drill some weep holes on the bottom...
Are there any kits for this kind of thing? Does anyone have any tips? (Other than walking up cold and knocking on strangers' doors and asking "hey how didja get your through the wall A/C's covered...") Hopefully you know what I'm trying to describe...
TIA, Banty (feeling very inarticulate today..)
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