Rudy the Robot Battery Cover

The red, yellow, and orange plastics are polished, and have a similar sheen to the original toy (though not perfectly smooth, the difference is negligible from a normal viewing distance).

The black plastic has a more matte surface (it's not polished), but is otherwise the same material, and could be polished manually.

While there is no plastic available to match the dark blue variant, the white plastic can be dyed. The best bet may be to paint a black print, however.