I picked up a hot/cold pack in the shape of a bear for one of my friends for their baby shower. Then I remembered one that my niece used to use that had cloth around it. She used it for everything. She is now 14 and I still think it's in their freezer.
I used some felt because I wanted to keep the edges raw. I tried to sew around all the pieces with my sewing machine, but that wasn't working for me. So I ended up just gluing the pieces on. I left an opening at the bottom, just in case she wants to remove it for cleaning or replacement.