I'm so sorry - it was a tv program called "Ultimate Factories". It would have been so nice to know about this before making my baby blocks(posted under pictures a few days ago). I had some of that stiff batting that is packaged in precut sizes for making crib bumper pads. It's about 1" thick and I wanted to stack 5 of them inside each block to hold it's shape. I wound up putting two in and filling the gap with a mix of batting and polyfill. I'm guessing that using this plastic trick I could have at least gotten 4 into the blocks.