I've had my eye on this tutorial for months now, and I finally got around to making it! (Probably because I was procrastinating on something else....) I used two queen-sized thrifted sheets to make this - it's 80 inches in diameter, as we have a LOT of Legos. I have enough left from both sheets to make a somewhat smaller version, also....We'll see how long that takes. ;)
The tutorial is pretty simple. Basically, this is two circles sewn together. You then use premade or self-made bias tape or ribbon or whatever for the drawstrings. I made my drawstrings from broadcloth I had leftover from the "green" party bags project. I liked the idea of using something up (that totally finished off my leftover orange) as well as getting a pop of color. And orange is Thing 2's favorite color, so he'll like that touch. (As an aside, I cut my strips on the straight grain and then ran them through the bias tape maker. I didn't feel that they needed to be cut on bias as these were only going to be used for drawstrings.)
And here's the sack all cinched up, with toys inside. I'm hoping this works out in practice as well as it does in theory! I'm also thinking that this will be a great idea for a baby gift - something the parents can use into the future. If I give any as baby gifts, though, I'll put a caution in the accompanying note to use these only with supervision, as the drawstrings could pose a strangulation hazard.
Someone had posted a comment to the tutorial, saying that their self-made bias tape didn't move very easily through the casing. I don't know what kind of fabric she used. My thrifted sheets are almost certainly a poly/cotton blend, and I believe the broadcloth was also a poly/cotton blend. The drawstrings move very easily through the casing.