Where can I get, for example, a 1/2 or 1/4 sized sheet of drywall or a small amount of fiberglass insulation? I only see whole sheets of drywall which I don't need/want/ and won't fit in my car. And the insulation seems to come only in bales, which is also way too much for my attic/roof access door. Buying an entire bale of insulation and throwing the rest around the attic is not an option either because the attic is only 6 inches deep. Using some other material (styrofoam) won't work for an access door because it's not hinged so I really need something that's flexible.
I don't see these things in small quantities in Home Depot or Lowes.