Can you 3D print in gold at home? Not exactly. But we have found an example of how you can use 3D printing technology to cast gold.
In a now-old post on the Ultimaker blog, jeweler Paul Steenbrink (a.k.a. Cardillac) experimented with a technique for preparing gold jewelry:
The 3D print is invested in ceramic material and heated to +1500C and vaporizes, leaving a mould ready to cast from.
That's it! Put the 3D print (PLA) in a fluid ceramic and let it harden. Then simply burn out the plastic by raising the temperature sufficiently high. This leaves the ceramic with a void in the precise shape of the original 3D print.
If you've designed the model with "sprues" that extend from the model, you can use them to pour liquid metal into the ceramic mold.
Once the metal has cooled and solidified, crack open the ceramic to reveal your model in metal.
And that metal could be gold, if you can afford to purchase the necessary materials.