Tip o' the Brick is a semi-regular spotlight on a great piece of advice in the BrickTalk forum:
Tired of those tacky plastic accordion wings on your window a/c? Try plexiglass:
"I just put my a/c in for the summer and decided to try the plexi route. EASY. A plexi cutter costs a couple of bucks and cutting plexi is like cutting glass - score it 2-3 times and then snap it off (use floor protection and don't be behind the cutter). I used velcro to attach the plexi to the window frame. I wouldn't have believed it, but just the couple of extra sq ft of 'window' makes the room seem lighter and the a/c unit smaller. As far as noise, seems to be about the same as the curtains."
--posted by laanyc
Read the entire thread here.