One of the problems with gold paint can be getting an even, smooth finish. So for this linoprint, I used an iridescent oil pastel which I then blended smooth with a finger. Another advantage was that I didn't have to wait for it to dry before printing the linocut over it.
Note: I used oil-based relief-printing ink to print over the oil pastels, not a water-based ink. The pastel will shift and rub off a bit if you touch it, so the artwork would need to be protected under glass. Using this technique for a one-off card, I'd use one of those folded formats where there's effectively a mount on top of the image. Get the lighting right, and the iridescent pastel photographs beautifully, so making prints from an artwork is definitely an option.