does anyone know of a good way to get a really even metallic finish on a cake without using an airbrush?  I've been thing gold lustre dust with alcohol and painting it on (over fondant)  with a brush but it seems to go quite streaky. 

AThe edible sprays?

Ahttp://m.wilton.com/store/site/product.cfm?sku=pg_colormist

AThere is a gym cake and motorcycle gas tank cake in my pictures. It took several coats to get the silver to a "solid" look.

Maybe consider a Preval Sprayer?  It's technically NOT an airbrush, but you get the same effect = and they're relatively cheap.

http://shop.preval.com/products/preval-sprayer

The metallic sprays by PME, Americolor, ChefMaster, & Wilton work very well and are completely food safe and edible.

The Preval sprayer is not recommended for use on food because the pressurized air it uses includes ingredients that mix with the air that aren't food safe.

AMel, I pm'd you..

Thanks for all your suggestions.  I tried the PME silver spray and wasn't very impressed with the colour, but perhaps I should have applied multiple coats.  I'll have another go.