For spreading putty in fillets on models, I have a stainless steel dental spatula that I bought at a local 1940s-era hardware store. It has a flat rounded end on one side and a small flattened spoon on the other.
I decided it was time to make my own so that I could change the radius of the edge a bit. I took two nails, one an 8d finish nail, and the other a thicker nail (for the spoon end) and pounded the head ends flat on an anvil. Then I shaped them using a grinding wheel, files, and sandpaper. I drilled a hole in the end of a dowel and mounted the smaller one for now. I'm still experimenting with their construction, and will post more information (drawings and photos) when I get the design I like.
Garet