I made a bunch of these for my daughter's Cabbage Patch doll, and some friends requested that I draw up the template for them. *However, I rounded the front because people seem to prefer sewing FOE that way. ;)
I used anti-pill fleece and fold-over-elastic since they didn't need to be absorbent. They fit several of her other dolls as well. Like her American Girl doll etc. I also used cheap velcro from the craft store for the velcro ones, so they are easy for a toddler to fasten and unfasten by herself.