Mix silver luster dust with a tiny bit of vodka to make an edible paint and paint that onto your fondant.
I just finished a guitar (in my photos) and was also going for the metallic look. I used 2 techniques: 1) grey fondant and dry dusted silver lustre dust and 2) painting silver lustre dust mixed with vanilla onto white fondant/tylose. I found the grey fondant and dry dusting the lustre dust was easier and gave it a nicer look. You can also paint your fondant grey first, then dry dust with lustre dust. HTH
I agree with Cakesrock, Color your fondant gray first then dust with silver luster dust. Use a brush similar to a small blush brush. I have tried to mix the luster dust with vodka and I just don't like the way it turns out.
StaceyCakes75, how thick was your mixture? It really only takes a couple of drops of vodka. The mixture should not be thin, almost thick enough to be a paste.
If thats the case it was too thin. Thanks gotta try it thicker.
I use kopykake's airbrush silver cake paint...works great!
I also prefer the dry method
There is a silver metallic edible paint in a small jar for about 4.99, that you can just paint one. It works great. I use it all the time. I think you can get it from fancy flours.
This tutorial talks about gold, but its the same basics for silver.
When you dilute it with vodka or lemon extract the color is stronger.
If it's too streaky you might have too much liquids.
Hope this helps.