I apologize, I did search and there were so many different conversations about different angles of gold and luster dust and such that I'm a bit overwhelmed and really don't know where to start now.  I'm looking for specific advice on how to accomplish this and am happy to hear product recommendations too.

I have a cake next month, all buttercream, two tier 8" + 6" where the bottom tier is painted gold and the top tier is buttercream white with hand painted detail.  In the past all of my gold bits have been done with gold dust (marked for decorative use only) + lemon extract and are on decorations not intended for eating so it hasn't been a problem.  I understand that using this dust over the whole cake is a big no no, so I'm looking for ideas of how to do this while keeping the cake safe.

I've used the Wilton gold spray before which worked for what I needed it to, but it doesn't lend itself to hand painting and the color is too yellow anyway.  Edible gold leaf is going to be way too expensive.

It doesn't appear that there's any dusts that are truly edible (am I wrong), so am I looking at airbrushing?  I don't have an airbrush but by no means am I opposed to getting one and learning, but how to I get that nice metallic sheen to the cake?  And how do I handle the hand painted details on the top tier since that can't really be airbrushed?  I suppose I could make a stencil and spray it, but that's not super ideal.  My preference would be a paint-like product that I brush onto the tiers, but I might be asking too much.

Any help and direction really is appreciated!

Doesn't look like deleting this thread is an option, but after research it appears that my best option is to suck it up and cover the cakes with MMF and paint them with gold dust.  Guests will have to be told to not eat the fondant, but that's not anything that should strike them as odd.