Not sure if this is the right area to address this...We have three wall A.C.'s. Every fall I insulate them from the inside with either bat insulation or sticky sheets (normally used to insulate ventilation hot air runs etc.)of foam and cover them with the standard interior A.C. cloth covers.

I'm almost certain I saw a more professional looking solution in one of the TOH shows: You made an insulated box, I assume useing rigid foam insulation sheets. Can't find any info on how build them and/or attach them to the wall with an air-tight seal. Can anyine help me find the instructions I need to make them? Thanks so much!