Here is how I did it:
I bought a cheap .98 cent Santa hat and cut off the fluffy white ball at the end.
I cut pieces of brown felt to fit on the hat and then I used iron-on adhesive to attach the felt.
If you sew you could totally make a felt hat without needing a Santa hat...but I don't sew.
It came out pretty cute.
For Doc's shirt I just took one of my old red t-shirts and turned it inside out.
For the back, I ironed on the "DOC" letters just because I happened to have some.
For the front, I ironed on some felt circles to represent the buttons.
And here is the finished product.
Not too bad for only $1.50
(.98 cent Santa hat and a few pieces of brown felt. I had all the other supplies already)