Hi Oscar !
I could do the job fairly cheap with Colorfabb Filaments. Their filaments are blended with up to 80% of metal dust.
Meaning, that 80% of the coin is actual metal.
The varieties are:
Due to the high amount of metal those prints also have up to four times the density of normal plastics (3,9g/cm³).
The brass composite is the closest that you can get to gold at the moment. The price is fairly high, but reasonable when you concider that the filament is priced by weight and three times the density means three times the price per volume compared to normal filament. I would make a special deal for you depending on your order size (much material => much discount).
Contact me via my hub to order some test parts or answer to this comment / request a quote on the hub for more information.
If you order the parts normally they will come in a sand-like optic and they will look like plastic. For a little bit of additional cost I can smooth and polish the prints (depending on the model’s complexity the price varies, that’s why I do not offer a concrete pricing).
Take a look at the following pictures for the metal optics (the Copper filament got postworked with black paint for additional shadows, normaly it is very much shinier).
Due to low requests on those filaments I do not have brassfill in stock, but I can get it very quick.
Hope to hear from you,