Yes,, I have made 3 of these. One for my granddaughter who was 3 and has ADHD. Wonderful, very soothing, and said she felt like she was being hugged all night. My 11 yr old saw it and fell in love because it is very warm, and snuggly. The last was for my husband as kept sneaking the girls blanket to put on his legs. He suffers from restless leg syndrom and he loves his also.
Just google plastic pellets and you will come up with differant sizes and shapes. I just used the smallest round pellet and was very sucessful.
I would sew a row and fill it, sewing another line across to form the filled square.I used cotton on mine, afraid the flannel might rip.
They Are Great Blankets, and easy to make!