There are websites that provide instructions on how to make these blankets. Most are smaller than a comforter. Search "weighted blanket instructions." There are some nice patterns.

I have been doing some research into these blankets, since I want to make one for myself. It should be no more than 10% of your body weight, plus 1 pound. I'd use the polly pellets, because they are able to survive the wash. They also tend to make the blanket bulky or more "puffy." Some use river stone. Corn, rice, beans etc should not be used for obvious reasons.

The blanket works by providing deep pressure stimulation. It calms, and is especially good for sensory processing disorder, ASDs, CP, etc...

If you like to bury yourself in heavy bedding, and find it soothing and relaxing (to have the weight on top of you) this blanket will work for you.