I go to a grocery store and by broken chunks of dry ice by the pound. 2-3 lbs is good for several 1-gallon bags of sugar leaves (≈20g kief). I use a 220µm bag from a bubble hash set, some say 160µm get's you more yield but it is darker. You can get them separately from
http://www.wackywillysweb.com/index.php for cheap. I too looked and looked for the right sized container to slip the bag over but eventually just threw the stuff in the bag and closed the end with my fist while I shook. If you stop for twenty seconds at 20 second intervals, you suddenly get a huge load of green snow precipitating out of the screen. No shit....snow flakes. I shake over a 5 gallon bucket and scoop it up with a credit card. A pollen press will form it into nice sized pucks for storage in mini-zip lock bags.