Two years ago I bought a house built in 1890 and very quickly discovered that there is not a single square foot of insulation in the whole thing...unless you count ancient newspapers nailed to the walls between exposed studs. This is a bad thing in New England. Long story short, I had to demolish some walls, which exposed more studs and empty wall cavities. I purchased rolls of pink fluffy insulation, only to quickly realized that not one cavity in 12 was the standard width of modern houses, and the insulation material was either to wide or too narrow for every single one.
To complicate matters, I could not find the right knife in the mess created during the move from my previous home to this one. However, I knew where my rotary cutter was, and even had some old blades! I went to town on that insulation...pressing it almost flat with a 2 by 4, and cutting it just like fabric. Eventually every cavity was perfectly filled with pink stuff...trimmed, pieced, and held in place with tape to maintain the vapor barrier integrity. It was a work of art. And then I had to cover it all with drywall...sigh.