Selena, a.k.a. Merenwen-Melwasul on DeviantArt, came up with a craft take for a steampunk style top hat. You can see the process flow in the above picture and note that she used a cut-up yoga mat to add all the texture. She says:

When the basic of the hat was done and all the materials are glued on the hat, I’ve added contour lines en dots with the contourpaint. These dots will make the hat look like it’s been made out of metal.
Then I’ve painted the entire hat black to create a solid base. Next I’ve applied the metallic paint with my fingers. Some people use Rubb ‘n buff for this part but I like acrylic paint. As a finishing touch to enhance the metallic I’ve varnished the hat. There is also another reason why I’ve done that: It is rainy in the Netherlands so I had to make it resistant to rain).

You can get the complete supplies list at DeviantArt.