Hello if all you want is is to say is MFK you could allways just get some of the huge letters that stick to a window surface that are not permanent or the ones' that are depending on what you want but it's not hard to find large letter stickers like that you know. And if you'r putting it on the back like i figured you would be on the out side you can get the ones that are back wards so the would be facing the right way throught the front you know what i mean like the ones that go on the inside of a car window to be read from the out side. OR you can allways make some out of pinstriping if you'r artistic at all. Or go and get some of the big letter cut out for paint and tape the stencil on the back and then use some kind of paint that sticks to glass and paint the letters like that with the stencils i don't personally know what kind of paint to use but these diy guy's deffenitly do. Any ways these are things i came up with hope it might help
Sincerly
Jeffrey allen Braley